British English someone who is off colour is feeling slightly ill.

• I'm fine, thank you, but Elinor's a bit off colour at the moment.
• Bruce went to the doctor, feeling a little off colour, and was told that he had anaemia.

http://www.ldoceonline.com/dictionary/off-colour

* 'looking (slightly) ill' (literal meaning, referring to the colour of the person's skin – pale, yellow or whatever); or
* 'being/feeling (slightly) ill' (figurative meaning, as in Amor's example).

'a bit' here = 'slightly'.

As SirReal says, 'off-colour' doesn't refer to the person being white/black/Asian; the writer has simply forgotten to include the hyphen. English-speakers very frequently omit hyphens in terms such as this, either through ignorance or through laziness. Unfortunately omitting them can sometimes completely change the meaning of a sentence.

* 'Disease-causing poor nutrition' is poor nutrition that causes disease.
* 'Disease causing poor nutrition' is a disease that causes poor nutrition.

* 'A hard-working man' is a man who works hard.
* 'A hard working man' is a working man who is tough.

* 'A man-eating shark' is a shark that eats humans.
* 'A man eating shark' is a man who is eating shark meat.

* 'Three-hundred-year-old trees' are an indeterminate number of trees that are each 300 years old.
* 'Three hundred-year-old trees' are three trees that are each 100 years old.
* 'Three hundred year-old trees' are 300 trees that are each a year old.
etc.