The main panel in the plugin is the Sweep panel. All the available sweepers are displayed here. If the sweeper has nothing to sweep, it will be hidden by default. The same is for individual sweepers; they will be hidden if they have some tasks without anything to sweep.
Each sweeper has additional controls to show empty tasks, show help, affected database tables, and limitations. You can see all that in the example image below.
Each sweeper includes detailed information about the data it will remove, how that relates to the database structure, and why you should use it in the first place. Some sweepers have a limited scope of use and recommendation on how to use them, so it is very important to check all provided information to understand better the whole process.
When it comes to number of records and dataset size for removal, these values are estimates. Size takes into account actual data, and the potential index size is not included, making it impossible to estimate correctly. So, real space regained after sweeping is most likely larger than the estimate!
Finally, each sweeper has a small badge in the right corner showing the percentage number. This is the estimated percentage of the space to be regained from the total size of the affected tables.