Q. I believe there is an annual Second Pesach. Can you explain what it is?
A. The Torah provides (Num. 9) that if a person is ritually unclean or away on a journey on Pesach, he can still bring the Korban Pesach (Pesach sacrificial offering) to God a month later, and eat it with matzah and maror.
The problem arose during the second year that the people were in the wilderness.
Because some had become ritually impure by reason of contact with a dead body, they could not bring the Korban Pesach at its due time. They would not have been punished because they had been prevented from observing the commandment, but nonetheless they felt deprived and wanted a chance of doing the mitzvah they had missed.
Hence the Almighty gave them a special concession and allowed them a second chance.
These days the problem does not arise because there are no sacrifices without a Temple.