I understand that international students are supposed to know how to read, write, and speak English fluently by the time they apply to college in the US, so it may not be considered a big deal.
However, It is a big deal for me since I did not have all those extracurricular opportunities that many US students have, and I have spent most of my free time on it outside my school classroom of course (the education system of my country is pretty poor in terms of English, only 2% of students from public Schools graduate with a B1 level, and the great majority graduate below that. In private schools it’s fairly higher, but that is due to bilingual and IB schools which are super expensive).
I plan to mention how valuable it is for me in my essay, how it allowed me to access to better education sources, become the valedictorian, and apply (at least haha) to the US universities.
In a nutshell, Is it a bad Idea to add English as an extracurricular?
Learning English is a great accomplishment and a good topic for an essay but it is not an extracurricular activity.
@TomSrOfBoston thanks for your response, I’ll keep that for the essay then.
How did you learn English that might be considered an EC? Were you in an English club, a writing or poetry club? If a US student was involve in French club, travel to French speaking countries, taught French to a boys and girls club, that could all be listed as an EC. If you learned it by reading books, list that. If you learned it by watching TV, you’re going to have to be very creative to get that to be an EC.
Look at your entire life, in and out of school. What did you DO? Did you work, help with younger children, help teachers at school? All could be ECs.
ECs generally refer to non-academic pursuits.
@twoinanddone Oh that’s pretty good advice thanks! (During high-school I used to learn at the public library in the mornings some times between 7 to 9 AM and other times between 8-10 AM, there was a tutor there so I could practice pronunciation with him, then I had to come back to home and go to school from 12:30 PM to 6:30 PM. In addition to that, I had to take extra required classes twice a week in the morning from 7 to 11 AM so I used to read articles and watch videos on internet during those occasions when I couldn’t go. However, I didn’t tutor kids but some of my classmates instead 
)