When concrete5 renders your page's header, it automatically generates the html title tag, pulling in the site name you've picked as well as your page title. By default, it adds two colons between these two pieces of information, so the result is something like My Site :: My Page Title.
If you'd like to change that separator-- say to a dash or similar (or you'd like to customize the display of these titles in other ways), an easy way is to define its format by adding the following line in config/site.php:
define('PAGE_TITLE_FORMAT', '%1$s :: %2$s');
This is the default format-- with the first parameter being the site name and the second being the page. So if you changed it to:
You'd just get page title names. If you changed it to:
define('PAGE_TITLE_FORMAT', '%1$s - %2$s');
you'd replace the :: with -.
This should allow you to get your site & page titles dialed in exactly how you want them. Happy building!