1. To have a compulsion to do something that is too strong to ignore or avoid. The verb used after "help" typically ends in "-ing." We can't help intervening here, before you throw your life away on drugs! My mom can't help meddling in my love life, even though I'm 30 years old!

2. To have no control over or be unable to avoid some action. I know you're irritated, but they couldn't help arriving late—the whole city is locked in a traffic jam. I know it's silly, but I can't help feeling like I failed you somehow.