I think they are watching a match. They do not have enough money to buy the tickets. So, they are watching the match by climbing on their cycles, because the stadium boundary wall is very high.
they are watching something interesting .they are not allowed to enter in that area therefore they are standing on their bicycles and trying to watch what is happening in that area .
I would just explain to them how poetry is a way of writing in order to capture physical and emotional details unable to be written in factual writing. Hope this helps :-)
