The Replication Activity page graphs the recent number of packages that were sent and received over each Replication Connection. The number of points you see in the graph is based on your data refresh schedule. If you want to see more frequent changes in the graph, then change your data refresh schedule.
The purpose of this page is to provide you with the ability to view package processing activity over a period of time.
Things to look for on this page would include significant spikes in the package counts, as they may be unnecessary.