A Dedicated IP is when one person/company has their own private IP address that links them straight to their server. Having a Dedicated IP means you do not get the same build-up of a shared Ip.
A shared Ip is when lots of people have the same IP address to a server. this can lead to multiple people using it at the same time meaning connection can be slow. The more people using the IP address at the same time the slower the connection and the more problems you will face.
A Dedicated IP is the opposite. Because you have your own private link to the server you shouldn’t experience those same issues. This would allow you to have quick and easy access to the server whenever.