This is an empty package that depends on the current "best" version of mariadb-server (currently mariadb-server-10.3), as determined by the MariaDB maintainers. Install this package if in doubt about which MariaDB version you need. That will install the version recommended by the package maintainers.
MariaDB is a fast, stable and true multi-user, multi-threaded SQL database server. SQL (Structured Query Language) is the most popular database query language in the world. The main goals of MariaDB are speed, robustness and ease of use.