When editing the contents of a list, you need not wait until your previous change is submitted to the server to make another change. While you are making changes to the data, the list keeps submitting your changes to the server in the background. If you bulk edit several cells, such as filling several rows of a column by dragging the drag fill handle, the list might take several seconds to send all the changes to the server. In such situations, it displays the Pending changes link in the status bar.
Seeing this link does not mean you need to postpone adding or editing data until all previous changes get submitted. However, if you attempt to edit the formula in a calculated column, or refresh or close the view, you will see a message requesting you to wait until your changes are submitted to the server.