Because this is a specific file name rather than a widely documented software product, the exact "content" depends on the source it was downloaded from. However, based on common naming conventions for such archives, it likely contains one of the following:
If you are looking to using the files inside this archive, you should:
: A collection of LUTs (Look-Up Tables), brushes, or plugins for editing software like Photoshop, Lightroom, or Premiere Pro.
: Use a utility like WinRAR or 7-Zip to open the .rar file.
: Most "Selected" packs include a text file outlining usage rights or installation instructions.
: A "multipack" of audio samples, drum kits, or loops for music production.