Birthday on 12/21/21

For a meaning of the date itself, the Date Meaning Calculator can be used. But you must specify the whole year (2021), not the abbreviated version.

If you are asking about subjective meaning of the correlation of the number repetition or sequence, that would be whatever you say it means. Numerology can provide the calculations for the date, but not for subjective meaning.

There are many dates that people can have subjective meaning about, and there are people with birthdays on all of them. Examples are 2-22-22 and 7-17-17. If you'll think about it, you'll come up with many dates of that type.