Hmmm. Of course we can't know for sure, and at other times I'm as frustrated as the next person with the lack of context from many posters. However, by far the most common context for this phrase (and which immediately comes to mind) is what people say when they have arrived somewhere. It can be said to each other. For instance, a couple drive to a place and the husband turns off the engine and turns to his wife and says, "Well, here we are." Or it can be said by people just arriving at another person's house or people that they are visiting or meeting: "Here we are!", "Wow, that didn't take long at all", etc.
Wir sind da! / Jetzt sind wir da. OR Wir sind angekommen! I'll let the German native speakers figure out what is the most idiomatic thing, but something along those lines.
For passing something to someone I would say, "Here you go". That's colloquial. The same thing for searching for something in a drawer. On finding it I might exclaim, "Here we go. It was there the whole time!"