What is "prorogation"?

A prorogation is what you call the time between two legislative sessions of a government body. The act of to "prorogue" is suspending the current session. (ie. the parliamentary session has been prorogued) Each constitution will have varying requirements before this act can be invoked. In some countries it is required that all current business be resolved before prorogation can occur. (wiki)

Most recently in Canada the Governor General was request by the Prime Minister to invoke this act to stave off a vote of confidence which would have caused the fall of the current minority government and possibly force the Canadian voting population into it's 4 election in 4 years.

Basically prorogation is when the ruling government calls a 'timeout'.