When you create a self-custodial wallet, it generates a seed phrase. Those words encode the private keys for every account the wallet holds. Enter them into any compatible app and you recover full control of the wallet. That is the point: it is a backup that works anywhere, with no company able to reset it for you.
It is also the single most dangerous thing to expose. There is no fraud department and no undo. Anyone who reads your seed phrase can move everything, instantly and permanently. No legitimate wallet, exchange, support agent, or airdrop will ever need it. Every request for a seed phrase is a theft attempt, without exception.
Store it offline, on paper or metal, never in a photo, a note app, a password manager synced to the cloud, or a message to yourself. A wallet risk check reads only public data and never asks for a seed phrase; if any tool asks you to type it in to scan or connect, close the tab.