The third book of the Hebrew Bible is generally called Leviticus, but far more revealing is its Hebrew name, Vayikra.
God has not given us this interlude in the narrative between Exodus and Numbers to provide laws or procedures for the Levites. Nor does it have that much to do with instructions for the priests.
Rather it's about God's call to Moses and to us. It's Vayikra - He called. Beneath the ancient practices that occupy much of the book, especially the sacrifices, it's about God's call to us to come near in sacred space.
If we are indeed to become a kingdom of priests and a holy nation it stands to reason that we would receive and accept this invitation, come near to God, and be instructed in the Divine ways. This is essentially what the book of Vayikra is all about.
In the first portion of the book, we are taught of several times we may hear the call and how we might respond, generally coming forward with offerings.
The offering for the first such time is dubbed a korban. In Hebrew, this means to bring near. We bring an olah, an offering just for God, and one for no particular purpose other than to come near. People of God, whatever their means, feel this need and express it voluntarily with an offering, whether with devotion, prayer, meditation, resources of value, or some other service.
We are taught of an additional offering of well-being. When we're thankful, appreciative of wholeness and peace and harmony, we want to come near the Source of all our blessings. Through this offering, we do so, celebrating with our community and those "priests" who help us come near to God.
At other times, we may have missed the mark in terms of our duties to God or have been unmindful or careless in these duties. We feel badly about the distance such behavior may have created between ourselves and God. Yet, even, and perhaps especially, at these times, God calls us back. And, we are blessed to have that path back through specified offerings.
Without question, the language on the surface here is of and for another time. We moderns don't go to the Temple of old. And we don't bring grains and animals. But, under the surface, God still speaks to us. God still calls us. God still wants us to come near.
Once we understand that, we can begin to explore in our modern lives how, and in what ways, with what offerings, and where. But we should never think God's call to come near was for another time and another people.