Good question. That can mean many things to many people. I would suggest that you ask one of the people who are uttering this phrase what they mean by it. In fact, ask several. You might be surprised to find that many of them don't apply the same definition to the phrase. If they do substantially agree, then you have the answer, and then a question here to interpret the explanation may be more appropriate.
One thing as a new member to a pre-existing team should NOT do is sit there quietly without asking such questions. People will assume you understand them, and then get on your case when you go off and do the "wrong thing". In technical and engineering teams, a common terminology is essential for success in your work. I know that when I start my new position in January as a senior performance engineer for a major world-wide telecom engineering corporation I will be asking a LOT of these questions and clarification of terminologies. That's the sign of a good engineer - to keep asking questions until the problem is clear in their minds.
