In Plesk, to export a database means to save a source database in a file which can be used for storage or distribution. To import a database means to restore data from the file to a destination database. You can import a database to the same or another database server. The only restriction is that the destination database should be of the same type, for example, MySQL.
One reason for exporting databases is to back them up. While Plesk for Windows offers a separate functionality for backing up databases, on Plesk for Linux, exporting is the only option for creating separate database backup files.
Also, databases can be backed up with other data during subscription backups and then restored separately. See the Backing Up and Recovering Websites section for details.
The export and import functionality is provided by the database management tool available through the Webadmin link in Websites & Domains > Databases.
Note: It is recommended that you import data into a new database.
For the instructions on how to perform import and export with database management tools, refer to the tools' built-in help sections.