What does the metro stops button mean for products?

If you have a pass or a daily travelcard, you can click on the metro icon in the top right corner of the product to choose at which metro station you want to get on, and by the time you get to the entrance you do not need to scan the code with your camera, you can simply present the animated image.

If you have location tracking turned on on your phone, you'll be offered the nearest metro station, but you can also choose another station.