hello everyone!
I'm a newbie with MacOS so I would like to ask for a question about how to open finder from terminal. I know, that's a simple question, but, I've never used Macbook, that's why I have some difficulties with it...

My man, I am a newbie as well, and I am still learning how to use terminal on MacOS, As I know you can use simple command 'Open.' in terminal and it will open Finder, or you can use other commands to navigate through the Mac using terminal so you will not need finder, I found this Information here https://osxtips.net/open-finder-from-terminal/ but there are much more information that could be usefull for you and everybody who use MacOS. There can be much more useful tips and commands for terminal that can help you become more friendly with MacOS.

MrDynamite1 is right 

To open a Finder window in the current directory of your Mac Terminal just issue this Mac open command:

open .

I hate working via terminal. I try to ignore this if it's possible