Suppose you have some topic on a forum that, for some reason, users want to have on the first page of that particular forum, because the first post of that topic is of major importance. Of course that topic can be made 'sticky', like some topics on this forum.
But if that post is not 'sticky', than after some time it will disappear on the 2nd page of forum topics and after that it will disappear into oblivion. What users of a forum can do to prevent that topic from disappearing is posting irrelevant reactions to the first post of that topic, the only reason being to keep that topic on the first page of the forum.
That is called bumping, because for some reason, the users started using the word 'bump' instead of some other irrelevant reply, because their reply wasn;t important at all, just the first (few) post(s) on that topic.
I don't know if that made any sense.
anyway. In your particular case, 'bumping' is used not to ensure that the topic remains on the first page, but to get a new page as soon as possible. Again, what is in the reply of the 'bumps' on your topic isn't the essence, just the fact, that they exist. Some kind of analogy there.