Okay kiddo, let me tell you about Taxila! Taxila was a place a long time ago, kind of like a city, and it was in a bigger area called a "satrapy." A satrapy was a region that was ruled by a powerful government, kind of like a king or queen.
Now, Taxila was really important because a lot of people came there to learn. They had a big school there and people would study things like math and philosophy. There were also a lot of merchants who would trade things like spices and fabrics.
Because Taxila was such an important place, the government wanted to make sure it was protected. That's why they made it part of a satrapy - they could send soldiers to defend Taxila if they needed to. And in return, the people who lived in Taxila had to pay some money to the government as a type of tax.
So, think of it like this - Taxila was like your favorite park where you go to play with your friends and learn new things. But it's part of a bigger neighborhood, kind of like a satrapy, and the government wants to make sure it's safe and protected. And just like your parents might ask you to give them some of your allowance every week to help pay for things, the people in Taxila had to give some of their money to the government to help pay for the soldiers and other things.
I hope that helps you understand what Taxila and satrapies were all about!