When creating the wallet, you are reminded to make a backup, and it will only be stored on your device.
The secret recovery phrase and private key are the only proof to restore the wallet and control the assets. If you share your private key or secret recovery phrase with a third party, they can control and transfer your assets without your permission!
So, private key and secret recovery phrase are very important! By the way, you need to back up your private key and secret recovery phrase and store them in a safe place, cause you can only get your assets back by one of them!