Piezo buzzers are used for making beeps, tones and alerts. Its the same thing that's in your microwave, alarm clock or washing machine to alert you when your food is done, or laundry complete. This one is petite but loud! You can plug it into your breadboard easily. Drive it with square wave to make tones - that's it, pretty easy.
To use, connect one pin to ground (either one) and the other pin to a square wave out from the Feather microcontroller. For the loudest tones, stay around 4 KHz, but works quite well from 2KHz to 10KHz.
For advanced usage/extra loudness, you can connect both pins to a microcontroller and swap which pin is high or low ('differential drive') for double the volume.