Theres a 14day cycle.
You are allowed to have 14 activity within the cycle. And wait for the 14day to reset to unlock your allowable activity.
For example. January 1. Account was created. Within
Jan 1 to 14, you could have (example again) 30post and 14 activity. You could exceed post, but not the activity. Then on January 15 to 28 you could have 30post 14activity. Do you understand.
You could read this thread, https://bitcointalk.org/index.php?topic=178608.0
Merit is also different. You could check and fully understand it on the Meta section. Hope that help