Welcome to the forum!
Although a noob question is probably more at home in the General board, rather than the Advanced board .....
Anyway, read the tutorials in the Tutorials - Getting Started section of the Editors Depot (link at the top of this page) for a better understanding of triggers.
Countdown is the time in seconds between the Condition field becoming true and the On Activation field being executed.
Timeout is the time for which the Condition field must be true continuously before the On Activation field is executed.
Note that the order of the boxes is min max mid. Note also that in waypoints, the field is Timeout but it actually means Countdown. (I think)
When a trigger has, for example, West not present in the Activation Box, the trigger will return an array of all West units in its area. You can use this array in the trigger with the command
thislist
and you can use it elsewhere with the command
list triggerName
The array updates automatically, whether the trigger has been fired or not. (I think.)
For your particular question you will need one trigger for each side that you are trying to detect.
Trigger:-
Activation Box: East present
Name: eastTrig
Condition: true
Script:-
_count = count list eastTrig
Syntax, etc. not guaranteed but hopefully you get the idea.