Hello! The human readable time is done with a plugin. Meks Time Ago: https://wordpress.org/plugins/meks-time-ago/

You can instead update your theme files and use the following code but the plugin is nice and easy.

Example code for theme versus using the plugin:

  $post_date = get_the_date();
  $post_timestamp = strtotime($post_date);
  $now = time();
  $diff = $now - $post_timestamp;

  if ($diff < 604800) {
    echo human_time_diff($post_timestamp, $now) . ' ago';
  } elseif ($diff < 2419200) {
    $weeks = floor($diff / 604800);
    echo $weeks . ' week' . ($weeks > 1 ? 's' : '') . ' ago';
  } elseif ($diff < 31536000) {
    $months = floor($diff / 2419200);
    echo $months . ' month' . ($months > 1 ? 's' : '') . ' ago';
  } else {
    $years = floor($diff / 31536000);
    echo $years . ' year' . ($years > 1 ? 's' : '') . ' ago';
  }

The activity feed is BuddyPress. Although a little overkill, I wanted an activity stream and didn’t want to create it from scratch. So, I installed BuddyPress but deactivated most features. I also don’t use the BuddyPress login, register, or profile pages.