you could measure the width of the bottom bracket shell on your frame. if it's 68mm, it's english. if it's 70mm, it's italian. or you could go by the rule of thumb that most italian frames use italian BBs, while most others use english.

to determine if it will work or not for your particular application:

1) for the BB to fit the frame, all you need to know is the threading - italian or english for most modern frames. for the BB, italian ones say 36x24T on them. english ones say 1.37x24T on them.

2) for the BB to fit the crank, you need to know what size spindle it takes. generally speaking, if you're buying a modern splined BB designed for a shimano double crank, and using it on a modern splined double shimano crank, then you shouldn't have a problem. if you're doing something funky, then you'll need to get the measurements of what width spindle a crankset requires.