We say, a flock of birds, a school of fish, a herd of cows, a swarm of bees,
But I am not sure what to say with sheep, is it a herd of sheep too or there is another specific word? By the way, if any one has another group name combination, (s)he is welcome to add.
A flock of sheep
See here: Group Names - Collective Nouns | Animals | Pub Quiz Help