There are 26 letters of the alphabet in English namely:
There are 5 vowel letters namely: a, e, o, i, u and 21 consonant letters which are the letters outside the 5 vowel letters. Letters are basically used for spellings.
Words in English are formed from letters. However, it has to be formed from both consonant and vowel letters.
E.g. B +O+Y = BOY
C+A+T = CAT
Neither consonant nor vowel letter can form a meaningful word alone.
X+Y+C = XYC
E+A+O = EAO