The best example is this, imo. you have a function call that is: `combineFirstAndLastName("John", "Smith")`
If your cursor is in the `"John"` part, and you want to change that, you can just input `ci"`, (c)hange (i)nside ("), to instantly start typing with John being removed. Lets say you want to change all the text inside the parenthesis, you just type ci), (c)hange (i)nside `)`.
There's commands like this all over, and you can compose all of them. For example, `ct"`, (c)hange un(t)ill ("), which will erase any text until the next available `"` on the line.
Or, (d)elete un(t)ill `char`. It's a whole language when you're editing with VIM, and while it might sound like that's very hard to learn, it's not. Because you can slowly add these verbs and sentences into your habits until it's completely natural
Once you learn the keys that correspond to your desired actions, everything else feels wasteful (Especially as I'm writing this on my phone). I turn on vim keys for anything that has it. It takes a long time to build up your vim vocab (I recommend you learn the simple stuff and incrementally look up better ways to approach things as you go). A great way to get started is vimtutor, which is built in when you install vim; just run vimtutor from shell and start reading. There's a lot more depth to what is possible, buffers, plugins, etc. but that's what stands out to me.
"How much wood would a woodchuck chuck?"
If you cursor is on the letter "H", you can type the "dw" to delete the word "How".
You can use "dt" to delete up to a letter. If your cursor is at the letter "H", "dtw" deletes up the letter "w" which will delete "How much ".
This barely scratches the surface. There is a steep learning curve involved but it's totally worth it if you need to edit text on a regular basis.