What's the grammatical component of "大勢" in the sentence "人が大勢います"?
Because I've learnt that 大勢can't be used as predicate. So I'm curious about the grammar

Question

Answer

你好！
大勢 is a noun. It means "trend, great number/crowd of people". So an example would be
そこには大勢の人がいた。There has been a crowd of people.

Answer

when we use 大勢 word, 大勢の観光客がいるね！(There are so many tourists.)今日のコンサート、大勢いたね！(It was so many people in this concert today.)
so 大勢＝たくさん. 大勢 is more polite word, use it when there are so many people.

hope you understand with this answer.... :)