Color is a tricky thing, especially if you involve people's perceptions of color. (For example color blind people see color differently)

Light has a wavelength which is related to color. Separately it has an intensity, which is the amount of that light.

Light can be a whole mixture of different wavelengths all at once. The result is what we call the color of the light. This is often expressed as a graph called a spectrum. On the x-axis is the wavelengths of light, and on the y axis is how much of each wavelength is in the light.

It gets a little bit tricky as a whole bunch of different combinations are seen as the same color by the eye. But they don't have the same mixture of wavelengths, and if sent to a prism will look different.

So that defines the color of the light but not the color of an object. Objects reflect and absorb different wavelengths of light differently.

You can make a graph of how much an object absorbs each color of light as a function of wavelength.

So the color of an object ends up being the color of the light you are looking at it underneath, modified by which wavelengths it absorbs.

We often refer to colors of objects as if viewed under white light, which is a roughly even mixture of most of the wavelengths. So a red object, absorbs most of the wavelengths of light except red ones. And it reflects the red light which is why your eye sees it as red light coming from the object.