That’s the number of black British [full] professors in the UK. Only one UK university has more than two. The numbers improve a little if one includes black [full] professors from outside the UK: it’s 75. The population of England and Wales, in case you’re wondering, is 2.8% black. (I’ve no idea why the article gives England and Wales stats for this bit rather than UK.) And 1.2% of academics overall are black.
The full article is here. It’s pretty good article, though I would have like to see more explicit discussion of the harmful effects in terms of stereotype threat and implicit bias. There’s a bit on the need for role models here, but that’s not quite the same. I think the discussion of causes would also have benefited from more discussion of the psychology.