As far as we know to date, ordinary matter is made up exclusively of two types of elemental particles: up (u) and down (d) quarks, and electrons.

The "quarks" can exist in three different forms (three "colours" red, green, blue).   The property called "colour" has nothing to do with what we normally understand as colour.
Electron

The quarks are grouped in threes forming in this way, depending on the types which group together, protons and neutrons:

Protons (two type -u- and one type  -d-).These quarks should be of complementary colours.
Neutrons (two type -d- and one type -u-). These quarks should be of complementary colours.

In the colour theory (with which we study the colours of the things we see) we call complementary colours those which show as white when combined.

Next