Vowel team OW makes two sounds.This vowel team says /ou/, as in “cow”, and is found at the beginning, middle, and ends of words and syllables. 

/ou/, /ou/, /ou/, cow

Across many words, vowel team OW most often says /ou/, like in “cow”. In some words, especially when OW is followed by L, the /ou/ sound is fairly reliable, as in “growl” or fowl”.   The common exception is “bowl”.