how can I understand higher order functions/lambas more?

Just try using them, they'll become clear as you go. Also take a look at sone of the standard library's funtions.

Talks that focus on higher order functions are helpful for putting the pieces together in my opinion. I found very helpful when I first saw it (it’s in Ruby though, there’s also a Javascript talk if you want to hunt it down). He discusses some higher order functions refactorings that have no effect by themselves but that set up other improvements later.

thanks for your answer guys! 🙂