The object snaps the motion path and a motion path marker appears at each end of the curve.
A lattice appears around the object on the motion path.
The lattice moves along the motion path curve with the object, changing shape as the path’s curvature changes. The lattice causes the object to deform so that it follows the contours of the path curve.
You can also flow an object around a path curve and build the lattice around the curve. In this case, the object flows through the lattice surrounding the curve, causing the object to deform as it passes through parts of the lattice. To flow an object with a lattice around the curve, select Animate > Motion Paths > Flow Path Object > and turn on Lattice Around: Curve. See Curve.