Is this all the code...if so, it doesn't appear that long so if you could next time paste the code itself wrapped in [ code ] 'code here [ / tags ].
Makes it much easier to see
Looks like your variables are searching for the last row and then the variable is used in the loop.
However long the last row is in the column, the loop will run that many times.
In your case it starts at 2 (probably because row 1 is a header) and then loop until in gets to the last row in column F.
A variable can be called anything you want, but the one caution, do not use any type of keywords. I don't know of a place to find these words, but overtime you'll understand what not to use.
In the example below you would not want to use the word Long as a variable name; however, you could write it as intLong and this would be fine.
Basically something that helps you know what you are doing.
http://en.wikipedia.org/wiki/Leszynski_naming_convention
or google
hungarian notation
Code:
Sub FindLastRow()
Dim LR As Long
Dim i As Long
LR = Range("A" & Rows.Count).End(xlUp).Row
For i = 2 To LR 'if LR is 10 then the loop will run 10X
'Do something here
Next i
End Sub
Do this, put a couple of letters in A1:A3. Select A1 then Ctrl + Shift + Down arrow once which will select down to A3 then once again which will now go to the bottom of the spreadsheet. Now press Ctrl + Shift + Up arrow and it will take you back to A3.
This in essence is what xlup is doing.