You have to understand about "port" not about "mysql Port"?
let me tell you one story about post card
let say in you home three people are living, you, your dad, and your mom
now three for you living in one home,
if one post card come to you then address on the post card consists of your home address and your name if one post card come to your dad then address on the post card consists of your home address and your dad name if one post card come to your mom then address on the post card consists of your home address and your mom name
when any of the above post card reach to postman then he has two works
1. he has to locate your home 2. he has to handover the post card to one who's name which has been mentioned on the post card.
Even though three people living in the single home, post man will delver to the specific person on your home by the help of Name on the post card
when it comes to computer, n number of computer application runs on the single computer, then how you'll find which one you want to deal with?
there your port number comes in picture, for each application running on your computer a unique logical number will be given, by using with that unique number you'll interact with the specific application on your computer.
lets say you installed the tomcat web server and install the mysql database server on your computer, now you want to interact with the tomcat server how you'll do?
you will write "localhost:8080" and if you want to interact with the mysql the u'll write "localhost:33036" here u'll find two thing one is "localhost" which means your computer, and two distinct number for two different application, means what two application living on the same computer , and if you want to interact with the specific application then you'll use specific logical name(port address) of that application.
so in simple word port number is the unique logical number, which will be given to represent the specific application on a computer.