What kind of "excuse me" is this? Can it be used when pushing past someone in a supermarket or is it for when you've done something bad?
It's the same as in English. The phrase means "take my apologies". You can use it in pretty much all instances as you would in English.
Could this expression not also be translated as ' Sorry, friend ' if you accidentally spilt water or beer on them in a restaurant or pub , for example?