that means that Tomcat inside of it has Apache Server embedded?
No, it means that there are two servers running (Tomcat and Apache httpd), and that all requests go to httpd (which so acts as a "front") and which passes all servlet/JSP requests to Tomcat.
If that's the case, it means that apache server is used for jsp and Tomcat for servlets or something like that?
httpd can't handle JSP (which is a
Java technology). It would be used to handle everything that's not a Java web app: other static content, maybe PHP, maybe Perl, ...
Also, can i install php module and use apache tomcat to serve php files?
Modules are an httpd feature, not a Tomcat feature. So, if you install a PHP module into httpd, then it can handle static content and PHP content, while it would pass on servlet/JSP requests to Tomcat.