"The man has many belts."
Translation:Mannen har flera skärp.
No, it's ett bälte.
The man has a belt – Mannen har ett bälte.
The man has the belt. – Mannen har bältet.
The man has belts. – Mannen har bälten.
The man has the belts – Mannen har bältena.
so it's never the same form.
Also, this word isn't taught in the course, it's a word that should only be accepted. The word we're trying to teach you is ett skärp (ett skärp, skärpet, flera skärp, skärpen). If you're shown bälte in this sentence, it's a bug, sorry about that.