A domain A record is essentially the location of your website’s hosting server on the Internet.
The A record refers to the IP address of the web server that hosts the page.
You can find your Zone server IP address here.
When you visit a website from the Internet, the domain name communicates with the IP address (in technical language, name extension) in the background. This connection locates the correct server, a request is sent to the server, and as a result your website is displayed to the visitor.
If necessary, you can change the A record of a domain that uses name servers in the Zone via domain management in the “DNS records” section.
Other services that operate on your domain are also identified by A records, such as your mail server or FTP server.
If the third party guide says to add a record with an @ name/host, omit the @ sign and just add the IP address into Destination text box.
The @ symbol is the root or apex symbol.
The meaning of the @ symbol is specified in RFC 1035:
@ A free standing @ is used to denote the current origin.
When changing DNS records for a second-level domain such as example.com, example.com is zone apex, so @ stands for example.com.
When DNS records for the subdomain foobar.example.com are changed, the @ sign equals to foobar.example.com.
When changing a DNS record in the Zone admin panel and the instructions say to enter the @ sign, then the Host text box has to be left blank, because the host of the root record already exists and is prefilled in the form.