How can something not be infinite but also have no end?

There are 3 theories about the shape of our universe one of them is this:

“The spherical universe is not infinite, but it has no end, in the same way that there is no point on the sphere that could be considered an end.” But what is beyond the sphere? How is it not infinite?

Citation (not formal): “Smithsonian Atlas of Space: A map to the universe from the big bang to the future” By Roger D. Launius. Page 12