They're rubbish bins (or perhaps textile recycling bins, but probably not) specifically for national, regional, and/or local flags.
Edited to clarify: No judgment, I am not making a political or societal argument, just posting about a thing I learned exists. If this post gets hijacked I'll ask the mods to lock it.
When I was a kid, I was told that you were supposed to burn a flag if it touched the ground so, being a kid and fascinated by fire, I would go to great lengths to make sure flags found their way onto the ground so I could burn them. I would have been immensely disappointed if this had been a thing instead.