u/Illustrious-Show-264

So, I was trying to drill 1 or 2 holes to hang up a curtain but the drill wouldn't go past a certain point. This has happened before at other points in my room. Almost like an impenetrable wall. My guess was rebar or something and I did catch a glimpse of something like that when I accidentally broke off a huge chunk yesterday but afterwards I tried drill a little lower and it still didn't work. Any advice on what that barrier is and how I can fix this missing chunk would be appreciated.

The paints been peeling off my wall since forever. What do I need to do to repair it and prevent this from happening again?