Unlike English, in Arabic there are three type of vowels:

(1) short vowel signs
(2) long vowels
(3) Diphthongs

(1) vowel signs "Haraka" also known as short vowels which are not part of Arabic alphabet but they  are merely oral, and used only in teaching texts for guiding the learner

(2) vowels letters  long vowels  one of their  function is to slightly lengthened the short vowels described in (1) above

(3) Diphthongs Alif and Ya "ay" and Alif and Waw "aw"