When you are a new English teacher, you may not understand the important of teaching grammar.
The reason why we need to teach grammar is not all languages follow the same grammar structure.
English's grammar structure is: subject, verb, object.
You can imagine how confusing this can be for students learning a new language. Not only do they need to learn a new alphabet but they need to learn a new grammar structure.
For example in English, we say "I have an apple".
In Korean, they say "Apple I have".
Teaching grammar is very important because students need to learn the right order in which to put words in order to make sense.