Shouldn't a Spanish friend be '四班呀人朋友'? I thought when referring to a person you need the 人
I might be wrong, but 人 seems redundant when 西班牙 can already modify 朋友. "Spain-people-friends" versus "Spain-friends".
Why is there not a "de" after Spain? To me this translates to "I have 3 Spain friends"
I'm not completely sure but in cases like this where "Spanish friends" (西班牙[的]朋友) could be confused with "friend of Spain" (西班牙的朋友) then the attributive 的 is drop while the possessive 的 isn't.
Do you say "friends of Spain" when you mean your friends is Spanish or lives in Spain?
The 的 is required between an adjective with 2 or more syllables and a noun. In this case, "Spain" and "friend" are two nouns that form a compound noun meaning Spanish friend(s). You will also see French cuisine is 法国菜 and doesn't require 的.
It doesn't show the sound button to hear the phrase at the beginning of the exercise. It happens in every circle since the last actualization.