Blank media tax is like a fee that some countries charge you for buying certain things like blank CD's, DVD's, or USB drives. It's kind of like paying a little extra money to the government when you buy something.
The reason why some countries have this tax is because people can use these blank pieces of media to make copies of music, movies or other things that they didn't pay for. And when people copy these things, the people who made them don't earn money from them. So, the tax helps the government to compensate for the lost money that artists and creators could have gained, and they can use it to fund certain projects like education, healthcare, and public safety.
In short, blank media tax helps to keep the creative industry running, while helping the government pay for important things that benefit everyone in the country.