How exactly to restore data from a backup? What does 'database copy' mean?

Data recovery from a backup is the process of restoring a database or files to the state saved in a backup copy. This is usually done using specialized tools or commands, which depend on the database management system (DBMS) or system used.

For example, for PostgreSQL, you can use the command:

pg_restore -d target_database backup_file.dump

Where backup_file.dump is the backup file, and target_database is the database into which the data is restored.

The term "database copy" generally refers to a full or partial backup of a database that contains all necessary data and metadata for restoration. This could be a dump file, a snapshot, or another form of saving the database state.

It is important to understand that recovery can overwrite current data, so it is advisable to ensure the necessity of the operation and to make an additional backup of the current state.