Censure is kind of like a time-out, but for grown-ups who are working in the government. When someone in the government does something that is considered really wrong or bad, the other people who work with them can say "No, that's not okay" and make them sit in a corner, so to speak.
Just like when you misbehave and your parents take away your toys or TV time for a while, censure means that the person who did something wrong might lose some of the things they normally get to do, like being able to speak in meetings or vote on important decisions. It's kind of like a punishment that reminds them to behave better in the future.