This may be a thread that may help you understand variables better.
http://www.hawkdawg.com/forums/viewtopic.php?f=66&t=337
No variable has any meaning/assignment until you give it one.
I'll try to help you understand variables more by looking at the Southeastern USA map you referenced and maybe going through it will show you how the variables are set up:
Silver
Game Variable 1 = 1 AND
Game Variable 2 = 1 AND
Company Variable 1 = 1
Company Variable 2 = 1
Years elapsed = 15
Look at the MEMPHIS TO event:
The test Condition - Company connects Memphis to Birmingham.
The Effect = Set Game Variable 2 to 1
Then Look at JACKSONVILLE TO ATLANTA
Condition - Company connects Jacksonville to Atlanta.
Effect = Set Game Variable 1 to 1
Next: LOADS OF COTTON
Conditions - LTD company Cotton hauled > 100
Effect - Set Company Variable 2 to 1
Finally: LOADS OF TIMBER
Conditions - LTD company lumber hauled > 50
Effect - Set Company Variable 1 to 1
So if you look at the other events you can see how the variables are being defined for that map. So after looking at the other events and seeing how the other variables are defined the victory conditions might be more understandable in the editor.
Silver
Game Variable 1 = 1 AND [Jacksonville and atlanta are connected]
Game Variable 2 = 1 AND [Memphis and Birmingham are connected]
Company Variable 1 = 1 [Enough lumber was hauled]
Company Variable 2 = 1 [Enough cotton was hauled]
Years elapsed = 15
These victory connections technically did not even need to use variables. It would have been acceptable to instead of using variables, just use the original condition tests that were used to set the variables. So the Silver victory event could have looked liked this and still worked:
SILVER EVENT
Conditions:
Company connects City to City - Jacksonville and Atlanta
Company connects City to City - Memphis to Birmingham
LTD Company lumber hauled > 50
LTD Company cotton hauled > 100
Years elapsed = 15
Effect:
Set Game Silver win.
There are times you need to use variables for something to work, but from what I see when I look at the map you referenced, the variables aren't actually needed.