pfTop is available in both the web GUI (by navigating to Diagnostics | pfTop), and at the console (it is 9 on the console menu). pfTop provides a live view of the state table and the total amount of bandwidth utilized by each state. If you are using pfTop from the console, type q to quit; this will return you to the console menu.
Most of the column headings in pfTop are self-explanatory. For example, the default view provides the following column headings: PR, D, SRC, DEST, STATE, AGE, EXP, PKTS, and BYTES.
PR stands for protocol; D stands for direction (in or out); SRC and DEST stand for source and destination, respectively; AGE indicates how long it has been since the entry was created; EXP indicates when the entry expires; PKTS