Mac storage basics · System Data and the storage categories
What is Music Creation in Storage settings, and can I remove it?
Short answer: It's GarageBand and Logic Pro's downloaded instruments, loops and samples. Remove it from the category's info button in Storage settings if you don't make music.
Music Creation is the sound library content downloaded by GarageBand and Logic Pro — instruments, loops and samples. If you don't make music, it's often several gigabytes you can reclaim.
Click the category's info button in System Settings → General → Storage to remove it. The apps download content again if you use them later. Logic Pro can also move its sound library to an external drive instead — see moving Logic's sound library.