The database is in the ONLINE operational state.
A snapshot stores the state of the data area at the time of the snapshot.
A snapshot is not a data backup. To restore your data after damages to the data area, you need backups. Regularly back up your database.
Note that snapshots are not part of data backups. If you have to recover your database using data backups, you lose all snapshots in the process.
More information: Backing Up Databases
To create and manage snapshots, the database system uses a shadow memory concept: a snapshot saves the current converter. Data changes that you make after the snapshot are written by the database system to other physical pages in the data area. For example, if you delete a table, the database system does not physically delete this table, but only flags it as deleted (and you can no longer access this table with SQL statements).
You set up a computer for training purposes.
Import a complete data backup from the original database onto the training computer.
Create a snapshot.
The database is now available for training purposes. The participants in the training course can now change data and start and stop the database.
After the end of the training course and before the start of the next training course, discard all changes since the snapshot.