One of the options to create accounts at Humanode networks.
Polkadot.js extension allows to create Humanode account with the main basic functionality - signing transactions. It's not responsible for storing your funds (just keystore operations).
An account is essentially a keypair, but the public key is used as an address, and the private key is kept private and used to sign transactions.
Use the link to download and install it in your browser.
Once installed, you’ll be prompted to accept the terms and conditions and then you’ll be able to create an account.
Check the substrate docs to find more details.