What does Genesis 31:46 mean?

Laban has suggested a covenant between himself and Jacob. Jacob has taken his wives, flocks, and children to return to Canaan. Laban, Jacob's father-in-law and employer, sees all of those as his possessions, though Jacob disagrees and describes the many ways in which Laban has cheated him over the last twenty years. Ultimately, they have agreed to disagree, in particular since Laban has been warned directly by God not to interfere with Jacob (Genesis 31:24).

Jacob responds to this pact by first building a pillar that will serve as a lasting witness to the event. Now he recruits the gathered "kinsmen" to also build a "heap" or cairn. Literally, a cairn is a pile of rocks built up to clearly indicate they have been placed by human hands, often as a waypoint or marker of a grave or, as in this case, a border. Jacob calls the kinsmen to participate in this covenant ceremony. It is between Jacob and Laban, but also between their clans. The ceremony included both groups eating a meal together by the cairn or "heap" of stones.