Learn Hardcore Korean: chingudeuri myeot myeongina wasseoyo?

친구 = “friend”
들 = plural marker (makes “friends”)
이 = subject particle (marks the word as the subject of the sentence)
So 친구들이 means “friends” as the subject of “came.”

Why do we use 몇 and 명 together? What does each part do?

몇 = “how many” (question word for numbers)
명 = counter for people
In Korean, you pair 몇 with the appropriate counter. 몇 명 literally asks “how many people.”

What is the nuance of adding -이나 after 몇 명 in 몇 명이나?

Attaching -이나 to a number or counter adds an emphatic or slightly surprised tone, meaning “as many as” or “no less than.”
So 몇 명이나 왔어요? implies you’re surprised or impressed by the number of friends who came.

Can we ask the question without -이나, i.e. 친구들이 몇 명 왔어요? How does that change the nuance?

Yes. 친구들이 몇 명 왔어요? is perfectly natural and simply means “How many friends came?” Removing -이나 makes it a neutral, straightforward inquiry without emphasis or surprise.

Why is the verb 왔어요 used in this form, and what are its components?