What is collective action, and what are some barriers of it?

I think you’re refereeing to collective punishment. The idea stems from the rules governing the treatment of refugees and prisoners of war and basically says that you can’t punish the whole group just because a few bad eggs are causing trouble. People often mistakenly attribute this to the ongoing issues with Israel and the Palestinians. Mostly the issue there is that Arab terrorists shelter in a civilian community and use it as a base from which to strike at Israel, then cry foul when the IDF come looking for them in that population. Israel builds walls to keep bombers out of its neighborhoods and the Arabs claim apartheid and collective punishment because it keeps them from living in the same neighborhoods.