XAMPP is a package of several programs like a webserver (Apache), a database server (MySQL) and others. With many of these programs, you can only run one instance at the same time. So if you for example have a webserver running, you cannot start another webserver until you stopped the first one. The same goes for the MySQL server, the FTP server and others. (Technically, you can start several webservers etc. if each of them uses a different port, but I assume you'd want to stick with the standard ports for the beginning).
The error messages you provided indicate that when you try to start XAMPP, there already is a webserver, a MySQL server and a FTP server running. So XAMPP can't start an additional webserver, MySQL server or FTP server. So you need to figure out if those servers are actually there, where they came from and if you want to use them or the XAMPP versions.
The first test is to point a webbrowser (Firefox, Chrome, Opera, ...) to your local computer without trying to start XAMPP and to check if anything answers. So point your webbrowser to
http://localhost. If a website appears, maybe the default "It works!" page from Apache, there is already a webserver running and XAMPP can't start an additional one. You can do similar tests with MySQL, the FTP server and the other components of XAMPP.
If there is actually a webserver running before you try to start XAMPP, you need to find out where it came from. I see two possibilites: XAMPP is already running, maybe it's tarted automatically at boot time, or the "standard" packages of Apache, MySQL etc. are installed and running. There are several ways to check that, one is to temporarely change a detail in the HTML files that one webserver is supposed to deliver. If you for example add a word, say "TEST", to the HTML that XAMPPs Apache is supposed to deliver, you can see whether that change appears in the browser or not. You can go on from there.