Vim is a text editor, which focusses on efficiency. At the core Vim beliefs that people spend more time editing, instead of writing new code. To let people be efficient at editing, Vim provides the user with multiple modes, each having a clear purpose. Two examples are normal mode and insert mode.
Normal mode (the default mode) lets you edit text using shortkeys, while insert mode lets you insert text. By having a separation between those modes, you can issue efficient keyboard commands to edit text without letters appearing on the screen from you using them.
It is really fun
For me the, main advantages of using Vim, is that it is really fun to use. Each time you edit text it is a mini puzzle for you to solve: what is the most efficient way of going from text A, to text B. After you are done solving the mini puzzle, you can think about all the time you have saved or at the very least haven’t spend doing any traditional text editing.
Vim shortkeys are everywhere
Vim shortkeys are everywhere. Vim is very popular, and tons of programs exists out there that use Vim shortkeys. Also, IDE’s often have support for Vim shortkeys, so even if you have to work in another program, you can still all the Vim shortkeys you have learned. Examples of this are Rstudio and Jupyter lab, both have pretty good support for Vim shortkeys.
I will give you my learning path on how I started with Vim. I believe these resources will get you from not knowing anything at all, to being capable of successfully using some very powerful Vim features, pretty quickly!
$ vimtutor on the command line. Vim comes with the vimtutor, a nice interactive tutorial to get you going in no time!
:help <topic> in Vim to view them. These pages have everything, if you cannot find it on stack overflow it is certainly in the man pages. I am certainly guilty of not reading the man pages, but I find myself often regretting not reading them sooner.