The Arabic language does not really need vowels to be read. Reading is directed by usage and grammar. But initially for beginners, they must know the pronunciation of the letters. And for this we give them the means of acquiring this usage and indirectly the grammar.

Short Vowels

Short Vowel A
Short Vowel E
Short Vowel U
Short Vowel “°”  (sukun)

Long Vowels

Long Vowels AA
Long Vowels EE
Long Vowels UU

Double Vowels

Double Vowels ANN
Double Vowels ENN
Double Vowels UNN

Other vowels

Vowel doubling the letter