Great question — answering as the UphillTech team:
These are steps to help people reach the overhead luggage compartments. Most people are unaware of their existence, but cabin crew, especially shorter members, use them frequently during boarding.
Full answer by phoog: https://travel.stackexchange.com/a/80705 (CC BY-SA 3.0).
Need it done for your business? UphillTech.
