Most plant leaves appear green because the chlorophyll present in them :

Chlorophyll, the green pigment in plant leaves, primarily absorbs light in the red (around 660 nm) and blue (around 430 nm) regions of the visible spectrum, which it uses for photosynthesis. However, it does not absorb green light effectively — instead, green wavelengths are largely reflected (or transmitted) back to our eyes. This is why leaves appear green to us. The absorption spectrum of chlorophyll has minima in the green region, making green the dominant reflected colour.