Advanced work means doing things that are really hard and require a lot of thinking and knowledge. Just like how you might have very difficult puzzles or games that are too hard for little kids, adults also have work that is more challenging than what you might see in a coloring book or easy math problems.
For example, if your teacher gave you a simple story problem like "If there are 5 apples and Johnny gives 2 away, how many apples does he have left?" Advanced work would be more like "If Johnny has 20 apples, but he needs to split them evenly between 4 friends, how many apples will each friend get? And what if Johnny wants to keep 2 apples for himself, how many will each friend get now?"
Sometimes, people have to work on really advanced things that involve a lot of knowledge and skill, like building a rocket ship or designing a computer program. These tasks require a lot of learning and practice, just like how you need to practice your letters and numbers before you can write a whole story by yourself.
Overall, advanced work is about challenging yourself and learning new things that are harder than what you've done before. It can be tough, but it's also really rewarding when you accomplish something difficult!