A paintball hopper (this may also be referred to as a loader) is a device that attaches to your paintball gun. This will store your paint before loading the paint into the firing chamber. If you’re looking to purchase your own hopper here’s a few things to consider.
https://www.bzpaintball.co.uk/blog/paintball-hoppers-what-you-need-to-know/
https://www.bzpaintball.co.uk/blog/paintball-hoppers-what-you-need-to-know/