I can only make sense of what he meant assuming it is 20h/week on top of the "study time" purely for the purpose of the PhD.
But then that seems like a lot, I wonder what's in the 20h...
In some countries (most universities in France AFAIK for example), "research time" is all of what makes your PhD. You don't have any course (it is changing a little, but seems quite superficially though).
That's because you're required to have a Master's to start a PhD in France, whereas in the US you get into a PhD program right after undergrad. So in the US, you end up taking some classes your first year or two, then you typically take the qualification exam, and then you start writing your dissertation.