The distance feature, as of now, is only available for India.
We contacted the developers of the site and as per them. The website utilizes a crowd-sourced dataset that contains an updated list of confirmed COVID-19 patients in India. In simple words, the algorithm of the website picks up your location data and then compares it with the location data of confirmed cases around you. Upon calculation, it shows you the distance between you and the nearest COVID-19 case.
Now, the crowd-sourced dataset contains the district name of the cases rather than the precise location. Hence, the algorithm compares the location co-ordinates of you and the patient's district. Therefore, the data is a rough estimate. As per the website, there could be an error of 5 Kms.
Apart from this, the website also provides a live global map of the COVID-19 cases and a live counter. Moreover, there a couple of graphs to intuitively present to you the age demographic and daily count of the cases. There is also a difference in the numbers, compared to the MoHFW site. But, this is more due to the Ministry not updating data at regular intervals.
Updated: October 18, 2021