Why is it so important to learn english?

It is not important. English can be useful in a commercial sense, but it is certainly not a lingua franca, and you should only learn it if you are drawn to it for other reasons. If you don't like it, don't pursue it.

It is so important to learn English because it is a medium of communication in the most parts of the world. There are too many books prescribed in English in the various themes like science, arts, politics, philosophy, fictions, etc. It covers almost all the aspects of the human lives.It is widely learned as a second language and is an official language of the European Union, many Commonwealth countries and the United Nations, as well as in many world organizations.

English is a West Germanic language spoken originally in England, and is now the most widely used language in the world. It is spoken as a first language by a majority of the inhabitants of several nations, including the United Kingdom, the United States, Canada, Australia, Ireland and New Zealand. It is the third most common native language in the world, after Mandarin Chinese and Spanish. It is widely learned as a second language and is an official language of the European Union, many Commonwealth countries and the United Nations, as well as in many world organisations.

That is why it is important.

English is one of the most widely-spoken languages in the world, and most foreigners learn it at some point in their lives. It's an important language to know if you ever travel or do business abroad. Additionally, if English is your native language, it's important to be able to speak it well, as it will help you in school, college, or career-wise.

Probably because English is the lingua franca

because its so easy its a way to communicate with others in different countries i cant see people learning chinese or korean