Okay, so Rest on the Flight into Egypt is a painting made by a very famous artist named Caravaggio. In the painting, there are three people: Mary (who is Jesus' mom), Joseph (who is Jesus' dad), and Jesus (who is a baby).
They are all resting under a tree that has big leaves and is casting a lot of shade, which is good because they have been traveling a really long time and they're tired. Joseph is sleeping, while Mary is holding onto Jesus who is also sleeping.
In the background, you can see some animals, like a cow and a donkey, and a river with some trees. It looks like they are in a quiet and peaceful place, far away from the hustle and bustle of the city.
The reason why they are resting is because they are on their way to Egypt. You see, a long time ago, when Jesus was born, the king Herod wanted to kill him because he thought that Jesus was going to take his place as king. So, Joseph had a dream where God told him to take Mary and Jesus and go to Egypt until it was safe to go back home.
That's why in the painting you see them resting, because they are taking a break on their long journey to safety. Caravaggio painted this to show how important it is to take care of yourself and your family, even if that means taking a break and resting for a little while.