You are accessing a XAMPP installation installed on your local network, not on your mobile phone.
This could even happen with a device on which you can’t install anything, like a TV or an old phone.
The message Prohibited access means that that installation has been modified and does not work the way you are accessing. The default would be /xampp to display server information. If you do not manage such an installation, nor know what is installed or how to access it, you can at most guess the access: /xampp, /phpmyadmin, /login.php etc. - but it is possible that nothing is installed.
To usefulness is that it’s a server, probably a development server. I don’t know about your network, but you might be in a public place and someone on that network has a server installed, or someone is testing things. For you it has no utility, but as XAMPP is probably not installed on your phone, it does not harm you too.
I understood, but repeating: How do I access it (as I said, is giving prohibited access) and what is the use??
– Diogo Alves
I added my answer. It helped?
– PeerBr
Now I understand better, as before I did not know about it, now at least I have a basis. I thank you!!
– Diogo Alves
Imagine, and welcome to stackoverflow.com!
– PeerBr