English vowels have "long" and "short" forms.
The long form is the "name" of the letter: The short form is as follows:
/o/ or /ou/
/u/ or /yu/
Long vowels are usually (but not always) indicated by a second (silent) vowel in the same syllable:
|jay||slow||pony||(Sometimes "y" and "w" can function as a second vowel.)|