An angle plate is a special tool that looks like a big, flat square. It's used to help make things straight and level. Imagine if you have two boards and you want to stick them together, but you don't want them to be crooked or wobbly. You might use an angle plate to make sure they're lined up perfectly.
An angle plate has two flat sides that meet at a right angle (like an L-shape). People use these sides to make sure that things are at a 90-degree angle (like the corners of a square). The sides are really straight and smooth, so they're great for making sure things are level and not crooked.
Sometimes, people also use angle plates to hold things in place while they're working on them. For example, they might put a piece of metal on an angle plate so it stays steady while they drill holes in it or cut it with a saw.
Overall, an angle plate is a simple but helpful tool that helps people make sure things are straight and level.