There are two main color systems, and they’re a bit tricky to learn, but you’ll be glad you did.
Additive color is what screens produce—they start at black and add in color to create the desired result. This is normally called RGB—for Red, Green, and Blue, the three “light primaries.”
Subtractive color is what printers use—the page starts white, and then you lay down layers of ink on top. This is normally called CMYK—for Cyan, Magenta, Yellow, and black.