Yeah, that's pretty much it.
It's based on a japenese puzzle called hanjie. It's kind of hard to explain in a post, it's easier if you can see the board.
Basically, if it says 4 5 on the left then along that row there is a group of 4 empty spaces in a row (although not necessarily starting on the first square) then 1 or more bombs, then a group of 5 empty spaces in a row.
This is the part thats hard to understand without seeing it: To work out which ones have to be empty I would count 4 from the beginning of a row then count one as a bomb and then count 5. I would then go from the opposite side, count 5 then a space, then 4. Any that worked out as empty spaces from BOTH ends have to be empty spaces. Sorry, that sounds very confusing - I usually explain this to people with a book of them in front of us so I can show them what I mean!
