It's a hardware wallet that is (optionally) never connected to the internet or any device that is (air-gapped).
It is purely for managing bitcoin wallets but not the funds. For that, you use a software wallet like Sparrow and connect them both through an SD card between the two.
It has many amazing features like VERY HIGH security and BIP 85.
If you want more info, just ask and I'll be happy to answer 😉
Coldcard.com