That is an Amazon Fire TV Stick 4K.
It’s used to turn a normal TV into a smart TV or upgrade a smart TV experience. You plug it into your TV’s HDMI port, connect it to Wi-Fi, and then you can:
* Watch Netflix, YouTube, Prime Video, Disney+, etc.
* Stream movies, football, music, and live TV
* Download apps from the Amazon App Store
* Use voice control with the Alexa remote
* Mirror/cast content from some phones
The “4K” means it supports very high video quality if your TV is 4K compatible, and “Wi-Fi 6” helps with faster, smoother streaming.