A PTR record or so-called reverse DNS record provides information about the host name that corresponds to a given IP address.
In the example below, the A record (the real record) of the domain www.vpsextra.com is the IP address: 18.104.22.168. Checking which hostname matches this IP address shows www.vpsextra.com. This is the PTR record for this domain.
The check can be done, for example, through the dig application:
dig www.vpsextra.com ;; ANSWER SECTION: vpsextra.com. 600 IN A 22.214.171.124