Open your Terminal and type the following command:
echo "export TERM=msys" >> ~/.bashrc
then restart your machine.
The shell is a program that presents a command line interface which allows you to control your computer using commands entered with a keyboard instead of controlling graphical user interfaces (GUIs) with a mouse/keyboard combination.
A terminal is a program you run that gives you access to the shell. There are many different terminal programs that vary across operating systems.
Some important reasons to learn about the shell:
It is very common to encounter the shell and command-line-interfaces in scientific computing, so you will probably have to learn it eventually;
The shell is a really powerful way of interacting with your computer. GUIs and the shell are complementary - by knowing both you will greatly expand the range of tasks you can accomplish with your computer. You will also be able to perform many tasks more efficiently;
More reasons: access remote servers, repeatability, documentation.
The shell is just a program and there are many different shell programs that have been developed. The most common shell (and the one we will use) is called the Bourne-Again SHell (bash). Even if bash is not the default shell, it is usually installed on most systems and can be started by typing
bash in the terminal. Many commands, especially a lot of the basic ones, work across the various shells but many things are different. I recommend sticking with bash and learning it well. (Here is a link for more information)
Acknowledgments: these lessons were adapted by Kara Woo from materials by Diego Barneche.