The colour of a star is an indication of its

The colour of a star primarily reflects its surface (effective) temperature: hotter stars emit more short-wavelength light and therefore appear blue-white, while cooler stars emit more long-wavelength light and appear red. For example, red dwarfs have relatively low surface temperatures (~4000 °C) and thus appear red [1]. Stellar spectral classification and observational resources explicitly link colour, spectral type and temperature (O,B,A... to M, with O hottest and M coolest), noting that hotter stars look bluer and cooler stars redder [2]. Colour is not a direct indicator of distance from the Sun or Earth, nor is it a direct measure of intrinsic luminosity (which also depends on size); therefore temperature is the correct physical interpretation.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 1: The Universe, The Big Bang Theory, Galaxies & Stellar Evolution > Red Dwarf > p. 10
2. [2] https://soho.nascom.nasa.gov/classroom/notsofaq.html