Depending on the context, it can mean "generally/broadly speaking" or "all in all", or it can be used before the speaker summarizes what he/she previously said (~"to sum it up"), or, if you ask a question and the person you are speaking to stops to think for a few seconds and then starts the reply with "в общем", it is similar to "Ok, it's like this: blah-blah-blah...." in English. Sometimes it can be used just as a filler phrase with no specific meaning — just for flow.