A sweep in athletics is when one team wins all available medals in a single event in a sporting event. At the highest level, that would be when one nation wins all the medals in an athletics event at the World Championships in Athletics. In athletics the maximum number of entrants from a single country in most events is three, allowing in theory for athletes from the same country to finish in all three top places.
List of medal sweeps at the World Championships in Athletics Wikipedia
Sweeps have only occurred ten times in women's events. The 10,000 metres is the only event to have had three occurrences, in 2001, 2005 and 2011. Ethiopia had most sweeps, at four.