Welcome to iMore! It depends on what device you're using and what features you have activated. If I'm playing the odds I'm guessing you're using an iPhone. In this case I'll describe what you see based on that.
From left to right
1.Do Not Disturb (DND)-Mutes incoming notifications and phone calls based on your settings
2. Rotation lock-Keeps your screen from rotating between portrait and landscape if you rotate your phone.
2. Location services-So your phone knows where you are. It will share this with different apps based on your permissions.
3. Bluetooth
These can be turned on and off in the control center, which is accessed by sliding up from the bottom of the screen.
Not pictured: If you have an alarm turned on you'll see a picture of an analog alarm clock as well