It's in the can

It is an outdated british slang phrase meaning "it is ready" or "it will be happen". It comes from old film industry slang, when the film was ready to be released.

Journalist: This movie took so long that it was almost forgotten...
Film director: Everybody made an excellent job, the film is in the can.

"She's in parties. It's in the can."
Bauhaus - lyrics She's in parties