Sitecore file explorer is accessible by browsing /sitecore/shell/default.aspx?xmlcontrol=FileExplorer
When you don't have RDP access to Sitecore servers or when you don't have access to CI/CD servers logs to see which version has been pushed to server.
You can easily browse sitecore files with file explore. The main scenario is when QA team assign a bug to you and you cannot replicate it on your local machine. It would be a good idea to download the rendering or dll and user reflector and compare it with your local code. If you know when was the last release you can check your commit history but I found comparing files on server easier to find the root cause of the potential issue.
you can update files or upload files with sitecore explorer but it's not good idea to do that because of following reasons.
- It's against all of the best practices
- You might have different content delivery servers and content authoring server. Updating files on one server doesn't automatically updates other servers.
- If you update any config file it resets sitecore app pool