A parish is a local church community that has one main church and one pastor. Parish members do more than just attend church. They organize community activities, social events, and — very important — coffee and donuts on Sunday mornings.
A parish is technically a piece of land. It’s a section of a diocese that has the right number of churchgoers to have its own church. But when you refer to a parish, you’re usually talking about more than the space itself. You're describing the people who attend the church, as well as the church property. So if someone says, "Our parish is thriving," it means there's a full congregation and enough funds to maintain the church in good condition.