|There are numerous ways to do what you are asking, everything from an IF to a VLOOKUP.|
For example, based on your example, with a Birthday in D1, you could use something like this:
All the ODD months would return Blue, all the EVEN months would return White.
To use VLOOKUP on just the Month of a date, you could add a column before the dates in the lookup_array and look that up.
C D E F G
1 Month Date Name Surname Team
2 =MONTH(D2) 1/2/2010 Xxx Yyy Blue
3 =MONTH(D3) 2/5/2010 Aaa Bbb White
With a date in A1, use this to return a Team color:
You could Hide column C if you don't want to see the Month Column.
I hope that helps.