'Years' in the Bible

Then after three years I went up to Jerusalem to visit Cephas and get information from him, and I stayed with him fifteen days.

Then after fourteen years I went up to Jerusalem again with Barnabas, taking Titus along too.

What I am saying is this: The law that came four hundred thirty years later does not cancel a covenant previously ratified by God, so as to invalidate the promise.

You are observing religious days and months and seasons and years.