As usual, there a couple of ways of doing this.
In SCR V8, there is a specific function to convert an integer to a month name.
In SCR V7, you can use a formula to convert the month numeric string into an equivalent month name. This is an ugly, nested if then else, kinda like
If Right({Sybase.Datefield},2) = '01' Then
'January'
Else If Right({Sybase.Datefield},2) = '02' Then
'February'
....
etc
....
Else If Right({Sybase.Datefield},2) = '12' Then
'December'
Else
'Invalid Month'
An alternative method that actually works best with dates is just to format the date field to print only the month (right click on a date field, choose format).
Because you don't have a true date field, you will have to fake one. The year or day of month doesn't matter, so we can always use the first day of the month, year 2000.
Date(2000, ToNumber(Right({Sybase.Datefield},2),0), 1)
I'm not currently working with v7, so I'm a bit uncertain as to whether the ToNumber(x,y) function existed (I think ToNumber(x) did, but the rounding option - where y is the number of decimal places - was an undocumented but working feature of version 7).