You're most likely hiding extensions for known file type in your folder view settings. But yes, if you edit that file and it opens an XML, that is the correct file.
Changing that value will change the port that your SolarWinds server accepts incoming Syslog messages on. I am not sure what you mean by your last sentence:
in this what I need to edit, when I am configuring syslog in my switch default port is 514.
Are you saying that you need to change the port on your switch configuration? I am not sure why you would really want to.
If you have established logging on your switch, and set your SolarWinds server as the recipient of those logs, then by default they will be processed as long as the service is started. If you still aren't seeing log data, I would start by checking firewalls before changing ports.