It probably uses the electrical contacts in post-AI bodies to tell the camera the maximum aperture of the lens so the camera can calculate correct exposure.

light levels are measured with the lens at max aperture, the camera needs to know what that is so it can work out how many stops to reduce aperture. Or to set speed in aperture-priority mode.

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The B&H description of that lens says

It includes a special chip that allows the lens to work with the camera's focus confirm, auto exposure, auto metering and auto white balance functions.

The Rokinon catalogue says

AE (Auto Exposure/"Chipped"): Capabilities include focus confirmation with fine tuning, exposure modes Auto/P/A/S/M and EXIF data.

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The Nikon electrical contacts are proprietary - meaning Nikon publish no information about it and you probably have to be a lens-maker under NDA to get details. SOme information is available from patents and other sources

You might like to see the answers to What are the electrical contacts in a Nikon F-mount?

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Aperture rings on F-mount lenses are redundant on most Nikon bodies produced this millenium. Early Nikon AF lenses with aperture rings typically have a lock so that the ring could be locked at the lenses smallest aperture. The camera controls the aperture. Later lenses (G designation) omit any aperture ring.