Help me with a Point of Sale app

Good day to everybody. I’m an entry level web developer and recently, my boss introduced my team to join another team of web developers and programmers to maintain a Point of Sale android app. For those who don’t know about Point of Sale, it is a tool (commonly a software) that helps automate a multitude of tasks for retail businesses such as restaurants. It can increase efficiency of the whole system and increase the workload with less stress and hassle.

Are there any people here who have ideas on what theories and knowledge from web developing I can apply to maintaining the app? I mean there will be an orientation in a few days but I also want to research ahead of time. My anxiety always kicks in and I really want to be prepared.

thoughts anybody?