Repression is a kind of holding back or holding down. There's repression of feelings (willing yourself not to cry), as well as social repression (where the government limits freedom or shuts out certain groups).
Repression is like suppression: you restrain, inhibit, or subdue something. Not allowing women to vote is a perfect example of political repression. If you have trouble expressing your feelings and keep things bottled up, then emotional repression is a big part of your personality. People often turn to repression because they're scared of what will happen if they say what's on their mind. Unfortunately, political and emotional repression can often lead to anger and even violence.