This paper briefly show you how to install neovim on manjaro linux.
At first take your terminal through shortcut or by selecting its icon, then type in:

$ sudo pacman -S neovim

You may after have to respond to a question like:

:: Proceed with installation? [Y/n] 

Of course hit "Y", also "y" works the same.

Now you have neovim installed on your machine, so to open neovim you need to launch a command which is "nvim", and not "neovim".
After being said you should be able to see your text editor opened:

At last, you have to install a module that the official site requires you to have.
So again inside your terminal type:

$ sudo pacman -S python-pynvim