It is a (kind of cute) German way of saying "there are." Yes, the literal translation of "Es gibt zwei Teller" would be, "It gives two plates," for example. But in English we would not say it that way; we would say, "There are two plates." In Pennsylvania, one used to be able to hear such things--in English--as, "Go a mile down the road until it gives a fork." That showed German influence.
From what I learned from comments from earlier lessons there is a difference.
Bei means "near/close to/near the vicinity of". When we translate beim as "at the" it actually means "near the vicinity of".
It is used to talk about reference points. Like "where are you?"-> beim Frühstück (near/at the breakfast), beim Meer(near/close to the sea).
When you want to say "at the table" as in literally right infront of the table then you use am(an+dem).
Hope this helps and correct me if I am wrong.