What is the account password after sshroot @?

This is especially simple. I followed the network course to see the account and password next to sshroot @. I will first talk about logging on to the server.
Then the teacher said that ssh would send a host address, and a user name should be specified.
Root user, he used his previous domain name, and then I forced him
I don't have a domain name?
Then I lost the same thing with him and succeeded, and asked me to lose the password? I don't know when to set the password ..................
I guessed a few of my possible passwords.
The instructor used @ plter.com. what is the general domain name?
When can this password be set? (it takes too long to understand, so I do not remember whether it has been set)

My understanding of php is just installed ......

Reply to discussion (solution)

What is the server ...... What server does php use ...... What can I find?
I pressed xampp, phpstrom, and cygwin

Ssh account @ address
The address can be a domain name, machine name, or ip address. What you said is either a real domain name or a local hosts.
For ssh logon and root logon, it is recommended that you do not use a password to log on. someone will constantly scan for weak passwords.
For security purposes, the default port 22 is not used, and password logon is prohibited. Instead, public key logon is used.

You need to set up your own server and domain name.

Ssh account @ address
The address can be a domain name, machine name, or ip address. What you said is either a real domain name or a local hosts.
For ssh logon and root logon, it is recommended that you do not use a password to log on. someone will constantly scan for weak passwords.
For security purposes, the default port 22 is not used, and password logon is prohibited. Instead, public key logon is used.

What should I do if I want to connect to a local server? Is it the dns server address?

In general, what should I deploy php on? Is this important ...... I think there are independent hosts, SAEs, and bae deployed there.
Is this a necessary step when I study it? I don't need to leave it alone.

You need to set up your own server and domain name.

What should I do for a local server?

Ssh root @ localhost