The Super Resolution feature in ACR essentially upsizes the image by a factor of four using machine learning, i.e. Artificial Intelligence (AI).
According to Adobe, Super Resolution builds on a technology Adobe launched two years ago called Enhance Details, which uses machine learning to interpolate RAW files with a high degree of fidelity, which resulted in images with crisp details and fewer artifacts.
"Basically it improves the quality of a photo by boosting its apparent resolution. Normally when you enlarging a photo often produces blurry details, but Super Resolution has an ace up its sleeve: an advanced machine learning model trained on millions of photos. Backed by this vast training set, Super Resolution can intelligently enlarge photos while maintaining clean edges and preserving important details", Adobe enthusiasts enthused.
Practically it means that anyone with a lower resolution camera, like the current crop of 24MP cameras, can now output huge image files for prints or any other usage that requires a higher resolution image file.