The letters of the English alphabet are either vowels or consonants or both. A vowel sound comes from the lungs, through the vocal cords, and is not blocked, so there is no friction. All English words have vowels.
These letters are vowels in English: A, E, I, O, U, and sometimes Y.
A, E, I, O, U shih Yingwern d muuyin zihmuu, Y yooushir yeeshih.