The airplane symbol  displays the option for Airplane Mode.

Just like your smartphone, turning Airplane Mode ON disables the bluetooth transmission so that you can safely continue to wear the Play pedometer on an airplane. 

You can also use Airplane mode if you wish to extend your Play's battery life. 

Airplane mode must be OFF for your Play to sync to your smart phone using the Striiv Activity Tracker app. 

The word that is highlighted signifies which one you have selected. 

In this picture, Airplane mode is OFF  

In this picture, Airplane mode is ON