beer is already plural, we would not say "beers"
Nope, beer is singular. It has a unitive sense, like water or soda, since it is a liquid, thus it seems less divisible. However, Becks and Bud are two distinct beers. At the bar you would ask for two beers not two beer.
Why "The woman has not the beers" is wrong?
English typically uses the compound form: "does not have"
I can hear "La donna no ho le birre" instead of "La donna no ha le birre". It is very difficult have it clearly IMHO.