what is the terminal command to install python3 frameworks??

You should mention which version of MacOS you are running .

In general what is in front of you when you type words and commands is the terminal, a terminal is a piece of software that is based on a textual interface and let's you run binaries and interprets your commands .

this is the usual icon for the default terminal on Mac

Now there are many terminals that you can pick or have installed in your system by default; MacOS has bash or, starting from MacOS Catalina, zsh is the new default .

This is the piece of software that Linux and Mac have in common, both bash and zsh are also available on Linux .

However what you are looking for is NOT a terminal or a shell ( another word for pretty much the same thing ) but what is called a "package manager" .

A package manager is devoted to administrative tasks regarding the software installed in your system and this part is highly system-specific so you can't just use the same commands for both the linux and the MacOS world, this is the part that they don't have in common, they have different package managers . Sometimes even different linux distributions have different package managers .

So, it can happen that you get the same shell on Linux and Mac but they have different package managers and different ways and commands to achieve the installation of software .

1 Popular package manager for third party apps on Mac is Brew https://brew.sh/ .

Brew is popular among developers because it provides a lot of different apps, but in the case of Python there is an even more specific package manager that is called PIP https://pip.pypa.io/en/stable/ .

PIP is not a system specific package manager, it only cares about the python world and python modules, you are probably going to use after you installed python to get extra modules maintained by the Python community .

If you install python from Brew pip will be included, follow the link above for docs and tutorials about PIP .