Learning English as a second language is a skill, not a knowledge. The reason for this is English is more than just the words. This is because English is a complete language system that includes aspects such as grammar, conjugation and writing etc. It is a skill because it involves the development of new and improved skills and competency in using and using it effectively. If you want to learn English as a second language, you should be persistent and practice it everyday. The more you practice, the better you get at it.