A colour wheel is a simple way of seeing how paint/pigment colours relate to each other. A hue is another word for a colour.
The PRIMARY colours are RED, BLUE and YELLOW.
Primary colours are the three principle colours that cannot be made by combining other colours. All other colours are derived from these three hues.
The SECONDARY colours are GREEN, ORANGE and PURPLE.
These are the colours made by mixing the primary colours.
The TERTIARY colours are YELLOW-ORANGE, RED-ORANGE, RED-PURPLE, BLUE-PURPLE, BLUE-GREEN & YELLOW-GREEN
These colours are made by mixing a primary with a secondary colour.
The COMPLEMENTARY colours are directly opposite to each other on the colour wheel.
So RED and GREEN, BLUE and ORANGE, YELLOW and PURPLE. They comprise of one primary colour and the secondary colour that is the combination of the other two primary colours.
The principle of complementary colours can be used to inform all your colour mixing choices to create a huge range of beautiful hues, e.g if a brown is quite orangey in colour, adding a blue to it can make shadow colours and muted variations.
With this principle you can, in theory, mix any colour if you have just the primary colours; but the result of doing that can be limiting. Pigments in paints are made from naturally occurring or synthetically made colour and there is a huge variety to choose from which can produce far more exciting results. Even the same oil paint colour can vary greatly from one manufacturer to another.