The "hierarchy of truths" is a Catholic theological principle stating that while all revealed truths must be believed, they vary in their foundational importance and their proximity to the core mystery of the Christian faith: the Holy Trinity and the Incarnation of Christ (CCC 90, 234).
Order, Not Validity
This hierarchy does not mean that some dogmas are less true or can be ignored. Rather, it means that some truths are based on others and flow from them. For example, the dogma of the Assumption of Mary is entirely true, but it depends upon and flows from the central truth of Christ's Resurrection (CCC 90).
May the Lord bless you and keep you.