A turntable is accessible through a thumbnail in the product preview. If you see a 360 icon at the upper left of the thumbnail, you can click the thumbnail to load the turntable in the Preview Window. Not all products have turntables.
The turntable loads and plays automatically. To manually view the turntable, drag the blue tag on the scrub bar at the bottom of the image.
If the Image Viewer icon appears at the upper right of the preview image, you can click the icon to view a high-resolution version of the turntable in the Image Viewer.