An .htaccess file is simply a text file containing Apache directives. This is a configuration file that is placed inside the web tree and applies configuration directives to the directory where it is placed and all sub-directories. Despite its name, this file can hold almost any type of directive, not just access-control directives.
Your Control Panel allows you to edit a .htaccess file both by filling a simple forms (in this case, the needed Apache directives will be added to .htaccess automatically) or edit a .htaccess content manually.
If needed, you can block access to your website for by requesting-browser attributes (header).