Okay kiddo, a censer is basically a fancy container that people use to burn incense. Incense is a special kind of material that smells really good when it burns, and people use it for different things like religious or spiritual ceremonies, meditation, or just to make a room smell nice.
So when someone wants to burn incense, they put it inside the censer. The censer usually has a lid on top and some little holes or slots on the sides, so that the smoke from the incense can escape and fill the room with its pleasant aroma.
Sometimes, people swing the censer gently back and forth using a chain or rope. This is called "censing" or "swinging the censer." It's usually done during religious ceremonies, and it's believed to be a way of symbolically purifying the air or spreading blessings around the room.
So basically, a censer is just a fancy way of burning incense and making a space smell nice and special. Hope that helps, kiddo!