Laura he
schengen visa might cover most of the European countries but he would still have to apply for individual countries like the US or Canada and others.
Here's a thread about it.
schengen visa
Canada doesn't have have a business visa, it would have to be a visitor visa with explanation what he will be coming to Canada for. I didn't look it up but I imagine the same is true of the US.
There's no universal "business visa" that I know of but the more he travels the easier it will be. The first one is the hardest since he's never been out of the DR.