Yes and no. We count them but it doesn't do any good because "sheep" is an irregular noun. One sheep, ten sheep. One fish, ten fish. Tooth and teeth, foot and feet, child and children, person and people, man and men, etc. A few animals are irregular nouns. Mouse, louse, goose, etc. Welcome to English. Good Q!

Hello HemR, 'Sheep' could be both a countable noun and a plural noun without a singular. The countable noun 'sheep' refers to the farm animal and its plural is 'sheep' as well. " a flock of sheep" The plural noun 'sheep' on the other hand refers to a group of people who copy each other, when one does something the others copy. "They are like sheep."