Cattle get abscesses regardless of their sex or age. I have seen them on baby calves as well as mature cows and herd bulls.
They contain variable amounts of pus and can be located anywhere on the body, though oftentimes they are on the face or neck. Rarely, they are associated with a traumatic event, such as a collision with a head gate.
Many attribute them to sharp-pointed material in the feed or forage that cause small puncture wounds which become colonized by pathogenic bacteria, which leads to abscess formation.
They are usually in the superficial layers of the skin but they can be in the fascial planes between muscles, in which case they can extend to deep within the body.
Not all abscesses need treatment but some are big and bad enough to require attention -- and caution. Cattle tolerate this type of crud remarkably well, though sometimes weight loss is apparent and often breeding cattle with abscesses will not be pregnant. However, there is no proof that abscesses in and of themselves cause abortion or infertility.
They seem to be an issue in some herds more than others and they seem to be related to nutrition. Well-fed cattle seem to have less of a problem. There may also be environmental and genetic factors at work in some of these herds as well.