It's almost anything out of the ordinary by definition, but usually refers to children somewhere on the Autism spectrum. They often struggle with being bullied in public school and depending on where they are on the spectrum can cause considerably increased workload for the school or even have outright behavioral problems complete with physical violence. That's extreme and rare thankfully, but even kids with relatively mild conditions can struggle in a chaotic public school environment.

Neurologically divergent individuals who do not adhere well to traditional expectations of behavior in social settings.

Given that this is a technical term that has gained colloquial usage, not everyone who is identified as (or self identifies as) neurodivergent is actually neurologically divergent in a literal sense, but behaviorally is close enough to be a moot point in non-academic settings.

This link has some good details on it - https://my.clevelandclinic.org/health/symptoms/23154-neurodi...

It is a term describing people with mental differences: ASD, ADHD, Dyslexia, Tourettes to name a few.