Is 'is' is a verb?

是的，"is" 是一個動詞

作用是連繫動詞or助動詞o

is is a verb to be = am are is was were
He is a boy. She is there. We are here. We are talking to him now.

是的，　'is'屬於英語中的助動詞，是動詞的一種．　
在一句英語內，人物(即主詞e.g. I, He, She, It, They, We)必須要加上一個助動詞。
句子結構
a.主詞+助動詞+名詞

e.g. Peter is a boy.