They're talking about how much load you can put on the output module. Outputs usually share a 'common' terminal, so there is a maximum rating on that terminal. That's your 'all points total' number. The 'single point' number is the maximum load each individual output can handle. All individual outputs at their maximum rated output is often more than the single common can handle.
For example, let's say you have an output module with 4 outputs per common that's rated 1A 'single point', and 3A 'all points total'. Even though you're allowed 1A per point, if you actually USE 1A at each point, you're pulling 4A through the common terminal. That exceeds the 3A 'all points total'.
I'm not sure what the 'adjacent points' is referring to. What specific module are you using?
beerchug
-Eric