THIS IS THE ANSWER FOR UR QUERY:
texts speak very loosely when they say there are five vowels. They
mean to say that there are five vowel letters (a, e, i, o, u).
Actually, y and w are also used as vowel letters. That is, these seven
letters and combinations of them are used to represent vowels. A
vowel is something you hear, not something you see. The symbols
(letters) you see are not, strictly speaking, vowels. They represent vowels, which is quite different .
There are rather more than five vowel sounds.
HOPE THIS HELPS:)