Beside the rear lens element of many (but not all) Canon lenses is a date code (as seen above) in the form of "UR0902". This code is also present on many other Canon products including camera bodies.
The first letter, "U", indicates that the lens was made in Canon's Utsunomiya, Japan factory. Prior to 1986, this letter is moved to the last position of the date code.
U = Utsunomiya, Japan
F = Fukushima, Japan
O = Oita, Japan
The second letter, "R", is a year code that indicates the year of manufacture. Canon increments this letter each year starting with A in 1986 and prior to that, A in 1960 without the leading factory code. Here is a table to make things simple:
A = 1986, 1961
B = 1987, 1962
C = 1988, 1963
D = 1989, 1964
E = 1990, 1965
F = 1991, 1966
G = 1992, 1967
H = 1993, 1968
I = 1994, 1969
J = 1995, 1970
K = 1996, 1971
L = 1997, 1972
M = 1998, 1973
N = 1999, 1974
O = 2000, 1975
P = 2001, 1976
Q = 2002, 1977
R = 2003, 1978
S = 2004, 1979
T = 2005, 1980
U = 2006, 1981
V = 2007, 1982
W = 2008, 1983
X = 2009, 1984
Y = 2010, 1985
Z = 2011, 1986
* assumption of continuation being made for future years.
The first two numbers, "09", is the month number the lens was manufactured in. Month 02 is February, month 11 = November. The leading zero of the month code is sometimes omitted.
The next two numbers, "02", are meaningless in determining how old a Canon lens is. This is a Canon internal code (that is occasionally omitted).
You now know the manufacture date for your lens - But - You cannot know how long the lens was in inventory, in shipping transit and on a shelf until it was originally purchased (without having the original receipt or a reputable person accurately informing you).
The Canon lens date code in the sample picture indicates that this Canon EF 24-70mm f/2.8 L Lens (I know because I took the picture - not from the date code) was made in Utsunomiya, Japan in September 2003.