AもBです / A is also B

AもBです

This looks like "AはBです / A is B" grammer. However, "も" is used instead of "は". ”も” means like "also, as well". So, this sentence means "A is also B.".

あなたも　にほんじん　です。

"あなた/you, にほんじん/Japanese". So, this means "You are also a Japanese.".