This means you should ask a question that requires a detailed answer, for example an open ended question would be, 'why do you want to learn English?' and the person would need to explain their answer. Instead of a simple yes or no question such as 'Are you learning English?' I hope this helps

An open-ended question is a question that gives possibility to give any answer. You as the person asking do not know anything, leave all possibilites to the answer. The answer can be a full sentence. Examples: What's your name? Where are you from? Open-ended questions have a question word: What, when, how, where.... The other type of question (closed questions) can only be answered with yes or no. This means that you have some knowledge about the answer, but are not sure. You want to confirm your thought. Examples: Is your name Rumpelstilzchen? Do you live in the woods? Are you a teacher? No question words here! You build the question with changing the word order. In your sentence, it tells you to use open-ended questions, with a question word, rather than just yes or no questions. Hope this helps