Adding php script to WordPress [closed]

This is a crude PHP Script, you will need first to have notions about WordPress hooks to implement it for example in a Plugin. Please learn about these topics.

Well, in response to your comment, that depends on the workflow of your project/website, to know exactly at what point fire the code.

This is an example, and not necessary should work as you expect

Basically, it should look like this code :

add_action( 'init', 'openning_hours_func' );
function openning_hours_func() {

    date_default_timezone_set('Europe/Stockholm'); // timezone 

    $weekday = date(l); // today
    //print $weekday; // Debug
    //print date("H:i"); // debug

    // Set open and closing time for each day of the week
    if ($weekday == "Friday") {
        $open_from = "11:00";
        $opten_to = "21:45";
    }
    elseif ($weekday == "Saturday" || $weekday == "Sunday") {
        $open_from = "12:00";
        $open_to = "21:45";
    }
    else {
        $open_from = "11:00";
        $open_to = "20:45";
    }

    // now check if the current time is before or after opening hours
    if (date("H:i") < $open_from || date("H:i") > $open_to ) {
        print "Closed!";
    }

    // show the checkout button
    else {
        print "Open!";
    }

}