Convex Hull
The Node creates a new geometry that includes all points of the initial geometry. Think of this as shrink-wrapping any shape in foil. All maximum positions of the points are preserved. Indentations and gaps in the geometry are lost. During this process a new geometry is calculated, which can also contain N-gons.
On the left you can see the original geometry, which consists of two cubes and a sphere that have been joined together. On the right, the same geometry was processed with the Convex Hull Node.