Student or Learner
"Where does grammar come in? Grammar’s ideal role in education is not as the hammer that teachers use to pound correctness into students’ heads. Grammar is best used as a language that makes it possible to talk about language."
Does the below statement mean to make students understand?
"the hammer that teachers use to pound correctness into students’ heads."
Not so much to understand, but to make them learn the correct way of doing anything - in this case, using grammar.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.