What an IP address reveals, and what it does not
Every site you visit sees the public address of your connection: it has to, in order to answer. From that address anyone can look up which network operator announces it, and the country the block was registered in. That is what this page shows you, using the same public sources as the IP lookup tool: Team Cymru for the ASN and the regional internet registries through RDAP.
It does not reveal your name, your street address or your exact location. City-level "geolocation" comes from commercial databases that guess, often wrongly, and this page does not use them. Behind carrier-grade NAT, a company network or a VPN, the address belongs to that gateway and is shared by many people.
IPv4 and IPv6
Many connections have both. Which one you see here depends on which protocol your browser chose for this request. An IPv6 address usually identifies your network more precisely than a shared IPv4 address does, because there is no need for address sharing.