According to the [documentation](https://polylang.pro/doc/function-reference/) there are 2 Polylang functions that can help you here :

*The first to "remember" the user language.*

**pll_current_language**

    // Returns the current language
	
    pll_current_language( $value );

    // ‘$value’ => (optional) either ‘name’ or ‘locale’ or ‘slug’, defaults to ‘slug’

returns either the full name, or the WordPress locale (just as the WordPress core function ‘get_locale’ or the slug ( 2-letters code) of the current language.


*Now this one to check if the user language exist for the page he clicked*

**pll_get_post_language**

    pll_get_post_language( $post_id, $field );
    
    // ‘$post_id’ => (required) id of the post for which you want to get the language

    // ‘$field’ => (optional) either ‘name’ or ‘locale’ or ‘slug’, defaults to ‘slug’