There is no specific "edge" on a sphere. Every single point is curved off, but there is no specific edge.
A square has 4 edges, each of which have the lines bending at 90 degree angles.
A pentagon has 5 edges, each of which have the lines bending at 108 degree angles.
And so on.
But a sphere has infinite edges, and therefore cannot be counted. This is why we usually say that the sphere doesn't have any real edges, mainly because it's impossible to count all those curves.