There is a rule in the Law that states when an oxen is plowing, you will not muzzle it so it cannot eat at the same time, presumably of the field it is plowing. Paul says that was written for "our benefit" meaning the people in the New Testament, and says it relates to supporting ministers of the gospel while they plow the field (minister the word of God). Paul, of course, also states that he supported his own ministry to avoid charges from others that he and his team were taking advantage of this privilege.
So Paul sees a mundane rule as having a secondary temporal-wise but more primary meaning intended for a later time, a sort of prophetic meaning if you would that he says reflects God's heart and mind more than the original purpose of the rule.
This is basic principle within the New Testament. It's not hard to grasp and is a very old Christian principle dating back to Jesus and his words, and arguably earlier.