Primary colours are red, blue and yellow.
Secondary are orange, green and violet.

Complementary colours are opposite each other on the colour wheel eg Red and Green, Orange and Blue, Violet and Yellow.

Similar colours are near each other on the colour wheel eg yellow and orange, red and orange, blue and green.

Contrasting colours are a third apart on the colour wheel eg RYB, orange, green and violet.

Colour accents are when small bits of colour are used in a photo such as a small patch of red in a large area of green.

Anything to add to that?