Okay kiddo, have you ever seen a sailboat? It's a big boat that has a sail or two that catches the wind and helps it move through the water.
Now, some sailboats have sails that are attached to a mast that goes up and down. This type of sailboat is called a fore-and-aft rig.
The "fore" part means the front of the boat, and the "aft" part means the back of the boat. So when we say "fore-and-aft," we mean the sails are attached to the front and back of the boat instead of the sides.
This design is useful because it allows the boat to sail better in the wind coming from different directions. The sails can be adjusted to catch the wind more efficiently, making it easier for the boat to move forward.
So that's what a fore-and-aft rig is, a type of sailboat design where the sails are attached to the front and back of the boat instead of the sides.