I've installed Polylang plugin, but I can't put language switcher in menu.
I've found in documentation this:
Your theme must support custom navigation menus for the following to work (for programmers, it means that the theme must call ‘register_nav_menu’) and must use a theme location in the function ‘wp_nav_menu’, i.e.
wp_nav_menu(array('theme_location' => 'primary')); is OK
wp_nav_menu(array('menu' => 'nav menu')); is not OK