A digital pattern generator is a special machine that can make a bunch of different patterns on a computer or electronic device. It's like a really fancy coloring book that can make its own designs. When you tell the pattern generator what you want it to do, it uses a bunch of tiny electronic switches and little math problems to make a pattern that matches what you want.
For example, you might want the pattern generator to make a funny face out of dots or lines. You would tell it what you want the face to look like and the generator would use its electronic switches and math skills to make the dots and lines in the right places to make the face.
Pattern generators are used for a lot of things, like testing electronic devices to make sure they work properly, or making designs on computer screens or video games. They are really good at making complicated patterns that would be hard for a person to make on their own.