"Run multimedia files, required for Windows"
This library is strictly necessary for your computer as it is indispensable for the multimedia composition that does not use OpenGL. In other words, it is the library that some videos and games use so that they can be played.
DirectX is a set of APIs or programming applications designed for Windows. These interfaces have the main function of facilitating programming tasks in the audiovisual sector: video games, music, images, etc.
Each of the DirectX APIs has a unique function and this makes it easy for them to fully comply with it, one for 3D, one for two-dimensional designs, one for sound recording, etc.
Currently DirectX already has versions higher than 10.0, so this version will be useful if you have an old computer or you play a game from years ago that asks for it.