The app will allow you to add a list of folders. Each day or each week according to your settings the app will automatically delete the contents of these folders. This is very helpful if you want to auto delete for example all of your temporary downloaded images in certain folder. Or if you want to auto delete your screenshots periodically. The app will automate this process.

A few tips:

Battery consumption should be almost non existent.

If you find out that the app is no longer deleting the files in the background after a few days then probably your device have an option to stop apps from working if they are not opened for a few days. Some of the latest Samsung phones have this option. To continue using the app you should add it to the battery exceptions list and allow it to work no matter if opened or not.

If you find out that after rebooting your device the app is no longer deleting the files in the background you should allow the app to auto launch after reboot. Usually this is not necessary but on some Xiaomi and Huawei devices there's an option to block apps from auto launching and this prevents app from working after reboot.