In the process of learning a language, there are many factors that you should not left out. It simply means that you should not only study one filed of the subject area. In English there are many fields such as vocabulary, idiom, grammar, speaking, listening, writing and so on.
In today’s world expectations are too high from a person to work in a company or to apply for a government official positions. So I urge you to learn English to enable you to perform many activity in your day to day life. Otherwise, you will probably not able to reap the enough fruits from the tree you plant. It is why always suggest students to learn as many subjects as they can although I can understand they have very limited time and money.