A man person is a man.

There's a の particle stuck in the middle of this word. Here it just means the noun before の is modifying the noun after.

Don't worry if that's hard to remember though. Just remember 男の人 means "man" (and that it's more polite than plain 男).

This word is actually two separate words combined with a particle. So, since you treat them like separate words, you read each of them with the kun'yomi readings (they are both single kanji words all alone). That being said, in level 4 you learned about the vocab readings for these separate words, so use that knowledge to remember the reading for this word as well.