A sphere in 3D space has one continuous curved surface. It does not have any flat sides, edges, or vertices in the way that polyhedra do.
Essentially, a "side" in geometry usually refers to a flat surface that bounds a three-dimensional object. Since a sphere is defined by a continuous curvature, it has only a single, all-encompassing surface. Think of it as one big, curved "side" that wraps around to enclose the volume.
Therefore, the answer is one.
