A provisional government is sometimes set up when a group of people want to replace the current leaders of a country or region. This kind of government is "provisional" because it's only temporary until the people can decide how they want their country or region to be governed.
When a provisional government is set up, usually someone is chosen to be in charge of it. That person's job is to manage the government until a new, permanent government can be formed. A provisional government might stay in power for months or even years until the people agree on a new, more permanent form of government.