In general, stereotypical feminine nouns you find in Russian end in -А(Я), typical masculine nouns end in a consonant (including Й), neuter nouns end in О/Е (Ё) and at least some classes of nouns have plurals that end in -Ы(И).
моя-мой-моё-мои seems to follow that scheme pretty closely, too.
Sometimes "Мои" read as 'moy' and then 'may' ... Any rules or grammatical laws about this? 'coz in English we all know that "the", in every noun which is pronounce with vowel words in the first place, will be read as "the" = 'di'. Else, started with consonant, just usual "the" = 'dè'.
Yes, correct. The stress shifts to the second syllable.
If you're ever unsure about the pronunciations on Duolingo (admittedly, the voice on here DOES make mistakes fairly frequently), I find Wiktionary to be very useful for checking pronunciation guides to see where the stress falls. (E.G. https://en.wiktionary.org/wiki/столы )
I thought "Ы" was one of the "silent" Russian letters (I could be wrong about that), and yet here it clearly makes a sound. Can you explain this please? Also, "Ы" sounds more like the English letter "i" in "this" or "it," or even better, ther French verb "est" ("to be" verb in the 3rd person singular), not "ee." Thoughts?
The simplest way to learn to produce a reasonably good ы sound is as follows:
Step 1: move your jaw forward as far as you can without having to call for a doctor to bring it back.
Step 2: while holding your jaw in that position, try to say "ee" like in "tee."
Step 3: remember that sound and try to reproduce it with your mimics remaining socially acceptable.
No, ы is not silent letter (you might be confusing it with ъ or ь). And it sounds much deeper and thicker than English i in it. There is no identical sound in languages like English, French, German, Spanish and all learners should take time time practicing it. You will have to use it quite frequently: in some Russian personal pronouns (мы ты вы), while forming plural (with some nouns) and in some singular adjectives in masculine gender (красивый). If you do not say this sound properly not only you will have a rather bad accent but also you can be misunderstood. I was born in Russia and lived there for some 25 years....:), so I know what I am talking about. Good luck!
You have to look it up on declension table, which lists the endings for nouns in all cases, genders and numbers (singular/plural).
Briefly: Neuter words never use either ы or и for plurals.
For feminine words ending in а the plural is ы. if they ending in я or ь, the plural is и.
For masculine words ending in - (none - e.g., стол) you add ы to the end to make it plural столы. Masculine ending й or ь the ending is и.
You have to be careful, because Neuter and Feminine share the я ending. Although Masculine and Feminine share the ь ending, both use и as the plural ending.
But it's best to get a declension table (there a lots on-line) and just painstakingly look them up one a ta time. There are so many other endings and such much common usage of the same characters to serve different purposes, it's best to focus simply on the problem at hand, and worry about learning it all later.
"Mine tables" does not make sense in English. The word "mine" can never be followed by a noun, while "my" is always followed by a noun. This is because "mine" is a possessive pronoun, while "my" is a possessive determiner.
You could say "the tables are mine", which would translate to "столы — мои", I believe.