Unfortunately not. ABAP is a proprietary language maintained by SAP, so it will only run within an SAP environment. However, like all programming languages, the experience you get writing ABAP will still make you a better programmer if you decide to develop in something else (e.g. Java).
I would only get the certification if I knew for certain the costs would pay off. Where I live, it's very expensive, and most companies don't require it among their developers.