Converting data into a form that is unreadable without a key. In transit it protects traffic between the user and the server; at rest it protects what is stored in databases, backups, and files.
Encryption is what turns a stolen database into a useless file and a lost laptop into an inconvenience. In regulated sectors its absence is itself a reportable violation, independent of whether anything was leaked.
We enforce HTTPS everywhere, encrypt sensitive fields and backups at rest, keep keys in a managed secret store rather than in the repository, and hash passwords with modern algorithms — never store them recoverably.