Whose address this is: the network it belongs to, the operator announcing it, where it is registered, and who to write to about it.
Nobody owns an IP address; blocks of them are registered to organisations by one of five regional registries, and each registry publishes who holds what. This page asks the right registry directly over RDAP, the successor to WHOIS for addresses, and shows the registration as the registry holds it: the block, its name and type, the country it was registered in, the dates, and the contacts, including the abuse address that a registry requires every block to publish.
Registration and routing are different questions. The registry says who the block was assigned to; the routing table says which network is announcing it to the internet right now, identified by its autonomous system number. They usually agree and sometimes do not, a block leased to a customer, or one announced by a transit provider on the holder's behalf, so both are shown, and each says where it came from.
Location is the least certain thing on the page and is labelled that way. There is no register of where an address is used; geolocation databases infer it from routing, registration country and measurement, and they are good to the country and usually to the city. An address in Dhaka will say Dhaka. An address on a mobile network or a VPN will say wherever the operator's gateway is, which may be nowhere near the person.
The abuse contact shown is the one the network's registry publishes for the block, and it is the address the holder is obliged to read. Include the full address, the exact time in UTC and what you saw; reports without a timestamp are usually unanswerable.
The holder of the block has not published a PTR record for that address. For a web server that is cosmetic. For a mail server it is close to fatal, and the reverse DNS page explains what to ask your provider for.
Yes. Ask with Accept: application/json, or add format=json to the address, and you get the same data as JSON, rate limited a little harder than the page.