Hello @abdelilahazzouzi3318!! Welcome to the Codecademy community!!
Everyone learns differently so throughout your coding experience you will find what works best for you.
When it comes to the many different coding sites, I found it best to stick to just one when you are first starting so you don’t get overloaded with many different concepts at once. I would pick a site that you like and start there.
For me I found CC to be my favorite with the way their learning environment works.
Once you understand the basic concepts you may find it easier to bounce back and forth, and start looking into the official documentation for the language you are using.
As for choosing a language, that depends on what you are wanting to learn to do.
The best thing to do would probably to decide what you want to learn how to do, and find out which language would be best for you to learn.
For me I found it easiest to start with one language and focus on that until I understood the basics of how it worked, and then I could bounce back and forth between different courses.
It again comes down to how you learn, some people can focus on multiple things at once, were as others may get confused and start mixing up concepts.