Keep it dry and out of sunlight.
As above , it's probably the manufacture date.
What's the date out if interest?
I doubt its a use by or indeed sell by date.
Date is 05/14
Is still in the box with the full kit.
Planning on getting it put on next week.
It's a genuine GM Cambelt kit.
Called a Vauxhall dealer who confirmed that the date on the packaging is the date they need to sell the belt by.