Hello. Unfortunately you did not submit the text that this question refers to. This makes it impossible for it to be answered. However I will try to help you as best I can.
Generally speaking, we can state that the careful reading of the text allows the reader to understand what the "League" is because at some point in the text the activity that this league promotes, or what it means, is presented. In that case, to answer that question, you need to read the text carefully and identify the sentence that promotes a characteristic of that league, which allows you to identify and understand it. This sentence can show what the league does, or has done, who the league members are, what its objective is, among others.