It's important to note that Screen Time Parental Control requires administrator permissions, such that only the person who has installed it (normally the parent) can delete it from the device. To do so, or to access the advanced options, the application requires the password you set when installing it.
From the options menu you can set the max amount of time each application can be used in a day. For instance, you could set Angry Birds to be playable for only 15 minutes, but the Calculator to be available at all times. Likewise, you can choose to limit Facebook but not e-mail.
Screen Time Parental Control also lets you set up a reward system by which certain actions (doing chores, cleaning your room, walking the dog, etc.) will trigger extra time to use some applications.
Screen Time Parental Control is an extremely interesting tool for any parents worried about their kids spending too much time on their Android devices.