What it means
An ordinary Android permission may grant a specific resource such as camera or location. An Accessibility service can observe screen content and perform interactions across apps to support assistive or automation features. That breadth can be necessary and beneficial, but it also makes an untrusted request dangerous.
A real-world example
A screen reader needs to announce interface text. A fake delivery app asking for the same access to 'confirm a parcel' has no convincing reason to control banking or messaging screens.
What to do
Verify the app, function and publisher before enabling a service. If it is already enabled without authorization, review the service list and affected accounts.
The distinction that matters
The word accessibility does not mean malware; many essential tools rely on it. Google nevertheless says the capability may read content and interact with apps, which is why some installation routes trigger restricted settings.
Google's restricted-settings guidance