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As a shape, a 'spindle' is a narrow ellipse with tapering ends, and this form is regular enough in galaxies that there is an entire class of 'spindle galaxies', elliptical galaxies that rotate around their long axis like a real spindle. There are also at least three individual galaxies named the 'Spindle Galaxy': one in Draco, one in Ursa Major, and a third - designated C53 or NGC 3115 - in the constellation of Sextans.
Counterintuitively, the Spindle Galaxy in Sextans is not in fact a member of the class of spindle galaxies. Rather than being elliptical, it is lenticular in form: a wide flat disc with a central bulge, but without the spiral arms more usually found in such galactic structures, and showing little or no star formation activity. Viewed from the Milky Way, the disc of the Spindle Galaxy is seen nearly edge-on, appearing as a long narrow line with tapered ends, and this is the source of its name.
The Sextans Spindle is by far the most prominent member of a small group of galaxies to which it gives its formal designation: the NGC 3115 Group. The entire group lies some 32 million light years from the Milky Way Galaxy.
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