A MySQL port is a network communication endpoint used by the MySQL database management system to establish connections with clients or other servers.
By default, MySQL uses port 3306, which is the port used at Hostinger for all of our Web and Cloud hosting plans - make sure to use this port when connecting to your databases remotely.
For local connections, such as in website's configuration file, you can use localhost as hostname and in that case, the port does not need to be added.
If you need full control to manage which ports to open or close on your hosting, you can consider a VPS plan.