Vim has a concept of an object and actions/motions that can be applied to the object. You can think of it as nouns and verbs. Vim objects can be letter, words, sentences or paragraphs. Say you have the following sentence:

"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.