It is pronounced only slightly. Basically the sound of the "n" changes towards the end because the "g" has no vowel it can form directly.
Maybe you can compare it to "akin" towards an "-ing" word in English. Or I just noticed while writing: the word "English" itself has the same phenomenon.
The infinitive of the verb is lesen and the stem would be les. However, this verb has a vowel shift. That means the stem vowel e shifts up to ie for the 2nd and 3rd person singular. The endings are not affected by it. Vowel shifts can only appear on e and a and they shift to i/ie and ä respectively. Problem is, you can not see if a verb has a vowel shift or not, e.g. sehen has one gehen hasn't. You can find a lot of references on verb conjugation in German. For present tense this text basically covers all the rules (even prefixes): http://yourdailygerman.wordpress.com/2012/02/03/german-conjugation-online-course/
what about "is reading" and "reads"? If there's no difference between them in German it should be consider by the context. It's more possible that man is reading the newspaper now then reads the same newspaper every day. I know that gramatically both versions are correct but still...
For anyone who missed it in the lesson tips and notes, there is no continuous aspect in German. This means that German doesn't have a different way of saying "he reads" or "he is reading" - both are er liest. If we translate from German to English, either form can be chosen based on what you think sounds better.
Of course, you can add more words to be more specific. "The man is reading the newspaper now" could be Der Mann liest jetzt die Zeitung, or "The man reads the same newspaper every day" could be Der Mann liest jeden Tag die gleiche Zeitung. But sometimes context from neighbouring sentences will help narrow down the meaning too (in the real world, if not necessarily on Duolingo's single-sentence exercises).
It's a coincidence that they are the same for this verb. This often happens when the stem of the verb ends in -s.
Plain (infinitive) verb: lesen
Stem of verb: les-
Typical du ending: -st
Typical er/sie/es ending: -t
So you might be expecting something like 'du lesst' and 'er lest' if the verb were totally regular. However two things are going on here:
1) A vowel shift from -e- to -ie-. This happens sometimes, and you just need to memorise it.
2) No additional -s- for the du-form, because there's already one. Again, you just need to memorise it.
User Karlchen123 posted this useful link, which explains it a little more.
Du liest can mean either "You read" or "You are reading".
Der Mann liest can mean either "The man reads" or "The man is reading".
German does not have a continuous present tense like English does, so usually either will be a valid translation. Duolingo just has to choose one example to display as the 'answer', even if there are multiple possibilities.
Are you English native speaker? If so, you're gonna have bad time. It's declination so it depends on the case. Usually you learn words in nominativ case, but in german there're 4. Nominativ, Genitiv, Dativ, Akkusativ. You can find the tables when you should use which one. just google "german cases table". The best example comparing to english - It's the same reason why you say: "> I < did something" but "Something was done to > me < ", but in German it's far more complex :)
and sadly you won't know for a long time. especially if you're English native speaker. there are 4 cases/falls in German + every noun has a "gender". so depending on what you're trying to say Artikel changes in the sentence. "Den" is used when noun has "der" as an Artikel in the Akkusativ case and in plural (die) in Dativ case. Examples: Ich gehe in DEN Wald (der Wald - forrest) Ich fahre oft mit DEN Zügen (Der Zug (singular), Die Züge - plural) - Train).
I'm not English native speaker and I understand cases and declination. When I write something I usually choose correct Artikel, but when I'm speaking ... boy oh boy. (I learn German since February 2016, I speak it daily since August).
Without context, you can't -- the German present tense can indicate either a habit or something that is happening now. Both translations will generally be accepted.
If there is a time expression in the sentence, then translate according to the rules of English grammar, e.g. Ich lese jetzt ein Buch = I am reading a book now; Ich lese jeden Tag ein Buch = I read a book every day.
The word liest means both 'reads' and 'is reading'. How does one judge the correct tense in a given sentence?
By seeing whether there is any time context that would require one or the other tense in English.
For example, "every day" would require simple present while "right now" would require present continuous.
In the majority of simple sentences on Duolingo, there is no such context, and so both tenses are plausible translations -- and will both be accepted. Both are "the correct tense" and you can choose either one.
For example 'Der Mann liest die Zeitung' translates as both 'the man is reading the newspaper' and 'the man reads the newspaper'
That is correct.
Why not "lest" instead of "liest".
Some verbs change their stem vowel (the last vowel before the -en ending) in the du and er, sie, es forms: from a to ä, from au to äu, from e to i, or from e to ie.
Which ones do this (and for verbs with stem vowel e, whether it turns into i or ie) is simply something you have to memorise.
There are probably historical reasons for those changes, but unless you want to learn Proto-Germanic, "that's just the way it is" is probably the best explanation.
lesen is one of these verbs: les- turns into lies- for du liest and er/sie/es liest.
(But ihr lest has the normal les- stem.)