hi all, hope you are doing well. I am new here and about to ask a very basic question. How do I build vocabulary

Ok, here is the story. I learned English as my second langauge. I am quite good and fluent in day to day English but the thing is since I learned English as second language, I really didn't read many things from all the domains! Somebody was telling me about "bale of hays" today. Now it is supposed to be a common knowledge but since I never read anything about country side or farming etc I took time to understand what he is talking about

Thing is I khow what the hays or straw is but have never used these words and hence I tend to forget them.
What I am looking for is to learn common words used in different fields. There might be many words used in construction, mythology, culture, festivals, farming, fishing, boating, medicine and biology.. the list is endless. I don't know the good approach to learn all these words. One thing I can do is to read different materials. Sometimes I think I should read all the course/school books starting from the first grade so that I gradually build my vocab and get to the par with the people who has learned English as their first language. I wonder whether anyone else is facing or had faced this problem and would really appreciate if you could tell me about how did you tackled this problem. Please let me know if you could think of any approach to tackle this problem.
Thanks for your time.
Sushil