I tried to post but got this. I could find nothing on it in the Help Center. What does it mean?
"You have reached your question limit"
Five hours ago from this post (so about when you posted here on Meta), you were stuck behind a question-asking ban. The exact reason for this ban is never clear (not even to us moderators), because it uses some 'secret algorithm' that it uses to determine if you're banned from posting questions or not that is not disclosed, and has a mostly-unknown rate-limiting system (that is partially explained in the Complete Rate-Limiting Guide over on Meta.SE)
Given that you got the "You have reached your question limit" error message, my assumption is that you tripped one of the reasons stated in the Complete Rate-Limiting Guide in the Asking section. However, there's no way for us to tell.
The system now shows that you should be able to post questions again. Keep in mind that if you have a number of new open questions you've made within a short period of time (even within a day) you might hit this rate-limiting system.