A pagination bar provides a way for your users to control the paging of a dataset. Elements that are connected to the same dataset as the pagination bar are affected when the user interacts with the pagination bar.
For example, suppose you have a repeater connected to a dataset and that dataset is set to have a page size of 5. When the page loads, the repeater shows the first 5 items from the dataset. If a user clicks on the next page button of a pagination bar connected to the same dataset as the repeater, the repeater then shows items 6-10 from the dataset.
You can also use a pagination bar without connecting it to a dataset. When doing so, you have to provide the pagination logic that runs when a user interacts with the pagination bar.