<?php

    $times = array(365*24*60*60    => "year",
                   30*24*60*60     => "month",
                   7*24*60*60      => "week",
                   24*60*60        => "day",
                   60*60           => "hour",
                   60              => "minute",
                   1               => "second");

    $passed = 12345;

    if ($passed < 5) {
        echo "Less than 5 seconds ago.";
    } else {
        foreach ($times as $period => $name) {
            if ($passed >= $period) {
                echo round($passed / $period) . " " . $name . "(s) ago";
                break;
            }
        }
    }
?>