There are 21 consonants in English, and most of them have predictable sounds, but there are one or two exceptions.
Y is both a vowel and a consonant.
In the word YELLOW, it is a consonant, but in the word HAPPY it is a vowel.
C can sometimes sound like an S as in CINEMA or as a K in CAT.
G can sometimes sound like a J, as in the word GENE.
H at the beginning of a word is very often silent, as in the word HONOUR.
X in the word FOX sounds like KS, and Q is never seen without U to give the sound KW as in QUEEN.
We will be looking at the sounds they create in more detail in later sections, but this information is meant to give you an idea of what consonants do.