I thought the post you are replying to is trying explain borrow checker. In a understandable manner assuming you know basic programming in Java.

I am a bit confused on what your complaint is aiming at...

Lemmy is social media, not school. Nobody owes an explanation. Mostly because the poster cannot know the knowledge level of whoever is gonna read the post. If every post has to be explained for every potential person that could read it, every post would be followed by a wall of text. Of all social media, the only time I've seen it happen is pugjesus' history posts. Which makes sense since he often references some niche history knowledge that very few people would know about.

Just googling "borrow checker" would've shown you it's something rust-related.