Explanation: Some other HTTP web server (Apache, IIS, another SQL Anywhere engine, etc) may already be using TCP/IP port 80.

If so, either stop that other process, or tell Foxhound to use a different port.

See also...
What HTTP port should I use for Foxhound?
How do I tell Foxhound to use an HTTP port other than 80?
IANA port number assignments
Can't start HTTP listener on address 127.0.0.1:80