Encryption is making some payload unavailable to any but those who hold the secret to unlock it.
Full disk encryption (FDE)
This means encrypting the entire disk of some system, at least most of it. It is then unlocked by a user wanting to use the system.
This is great if you loose your stuff while it is in an encrypted state. But it it is not then it won’t help you.
It is good to activate it but it’s no magic bullet.