Well:
60 seconds = 1 minute
60 minutes = 1 hour (or 3600 seconds 60 60)
24 hours = 1 day (or 86400 seconds 3600 24)
$time = time();
// Get days and remove them from the $time
$days = $time / 86400;
$time = $time - ($days * 86400);
// Get hours and remove them from the $time
$hours = $time / 3600;
$time = $time - ($hours * 3600);
// Get minutes
$minutes = $time / 60;
// Get seconds
$seconds = $time - ($minutes * 60);