Translation:The man is drinking water and eating bread.
The correct IPA pronunciations for mannen are
/ˈmɑnːɛn/, but native speakers shorten or throw away the ə and prolong the n sound to differentiate it from mann where n stops rather abruptly -
When the ə (Wikipedia article) sound isn't enunciated clearly, two n sounds sort of merge and are prolonged.
When you're practising at home, replace it with a more defined e sound and give yourself time so your ears can get accustomed to the almost unnoticeable ə between the n sounds.
Click here to listen to IPA symbols being pronounced.
Bokmål is the standard Norwegian, the language of litterature, studies, the language of "the city", close Danish. Nynorsk is the landscape language, more oral and practice almost everywhere, but... It is not a standard language. Each region, each town, each village has his own Nynorsk dialect and in 10km it is possible than the speakers don't understand each other. So, Nynorsk, besides, very used can't be an unit language. However there is a Nynorsk litterature, a standard language, but it is stil marginal... ;)
"Å sitte på vann og brød" can be used in that manner, but it's less common than in English, and has historically had a narrower meaning.
In Norwegian jails, being sentenced to X amount of time on "vann og brød" used to be a harsher form of punishment, as regular inmates were fed better. For a while, those sentenced to regular jail time were even able to get a discount on their sentence by opting to serve a shorter time on only bread and water.
Those sentenced to longer amounts of time on bread and water, would get single-day breaks to make sure they didn't die from their monotone diet.
This form of punishment was abolished in 1958.
Correct IPA pronunciation is
In the future, if you have problems with certain words, click the word itself (Duolingo will take you to the dictionary page) to isolate it and only hear its sounds being pronounced.
Norwegian has only one present tense which can be translated, depending on the context, as Present Continuous or Present Simple.
"The man drinks water and eats bread" and "The man is drinking water and eating bread" are equally correct. @MillionthMonkey is right about the differences between these two present tenses.
Always try to write sentences correctly (capitalisation and punctuation) to minimise the possibility of Duolingo marking your answers as wrong even though it can recognise typos which aren't grammatical mistakes as well.