Okay kiddo, so a benefice is a fancy word for a type of job. In old times, when churches were really important, people could work for the church and get paid for it. This job was called a benefice.
Sometimes the church would give people land or money in exchange for their work. It was a way to make sure people were taken care of while they worked for the church.
Nowadays, the word "benefice" is not used as much and it can have different meanings depending on where you live. But basically, it means a job working for a religious organization where you get paid or compensated in some way.