I need to change my .htaccess and there are two lines which I don\'t understand.
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule ^(.+)$ index.p
Not the place to give a complete tutorial, but here it is in short;
RewriteCond basically means "execute the next RewriteRule only if this is true". The !-l path is the condition that the request is not for a link (! means not, -l means link)
The RewriteRule basically means that if the request is done that matches ^(.+)$ (matches any URL except the server root), it will be rewritten as index.php?url=$1 which means a request for ollewill be rewritten as index.php?url=olle).
QSA means that if there's a query string passed with the original URL, it will be appended to the rewrite (olle?p=1 will be rewritten as index.php?url=olle&p=1.
L means if the rule matches, don't process any more RewriteRules below this one.
For more complete info on this, follow the links above. The rewrite support can be a bit hard to grasp, but there are quite a few examples on stackoverflow to learn from.