Secrecy is a word for a state or condition where things are concealed or hidden. CIA agents and conspirators know a lot about secrecy.
Since a secret is something some people don't know, secrecy is all about keeping things private or concealed. Being a spy involves a lot of secrecy. When information is important or sensitive, people try to create secrecy. Also, you can say secrecy is a quality people have, like courage. Someone who doesn't gossip has a good sense of secrecy. When all lips are sealed, there's secrecy.