A group of cows is called a herd, drove or team. Historically, people who took cattle to market on the open range were known as drovers.
The actual common name for this species of animal is cattle. A cow represents an adult female of the species who has birthed at least one calf. A heifers is a female who is yet to give birth. A bull is a male of the species that is not castrated. A castrated male is a steer. A calf is a young nursing cow, while a weaner is a calf that is weaned and under a year old.