a closed question can be answered with either a single word or a short phrase. a closed question can be answered with either 'yes' or 'no'.
eg-it's great weather, isn't it?-where do you live?-what time is it?
an open question is likely to receive a long answer. although any question can receive a long answer, open questions deliberately seek longer answers, and are the opposite of closed questions.
eg-what did you do on you holidays?
-how do you keep focused on your work?
-why is that so important to you?