These are applications that you removed from the system. They can leave behind "garbage", the folders of which can be deleted manually (Sometimes you have to search the Internet for paths). The uninstalled program can also be found on Google Play, it should be in your library and you can reinstall it.
These are applications that you deleted, but they left a trace in the phone's memory - folders with data, for example. You can go into the file system and delete these folders manually so that they do not take up space. Check if there is any information you need, such as photos or recordings.