By purchasing a Dedicated IP, your server will obtain the port: 25565. With that you can connect directly to your server without entering the port after the IP, e.g. you would only enter 192.268.7.2 instead of 192.268.7.2:25578. It also means you can use a domain name that you own without having to enter the port after it.
E.g. You would only need to enter mc.spartanmc.net into your client compared to mc.spartanmc.net:25566 without a dedicated IP.
Please note that a dedicated IP is NOT the same as a domain name e.g. mc.myserver.com, you must purchase a domain from a domain registrar for this such as http://namecheap.com. Follow our guide here on how to setup your domain after purchasing.