A divider is a small visual break that helps separate one part of a page from another. It is often a thin line, though extra space can do the same job. Imagine a line drawn between two sections in a notebook: it helps your eye see that one topic has ended and another has begun.
For example, a settings page might place a divider between “Account” options and “Notifications” options. A divider does not explain the sections; it only helps show where they split.
Use one when the page feels like a single crowded block. If headings and spacing already make the sections clear, another line may add clutter instead of helping.