To entail is to involve. A job at a movie theater might entail sweeping popcorn off the floor, probably because watching a movie entails eating popcorn in the dark. It’s a small price to pay!
The word entail, which comes from Latin, is connected to the idea of preconditions. If you want something, you better figure out what it entails. If it’s only 8 o’clock and you want to see a movie at 9, that will entail waiting for an hour. If you want to stay out of trouble, that will entail calling your parents and letting them know you're going to be late. That’s what being responsible entails!