In Ramadan the whole afternoon points at sunset, and the last hour before it is the slowest of the month. A live countdown to 5:09 pm at least turns that hour into a figure that moves rather than an open stretch of waiting. It reads your device's clock and updates without anything to press.
This is a display rather than an alarm. Nothing rings, buzzes or notifies at the end, and the page will not interrupt whatever else you are doing. If being interrupted is the point, set an alarm as well and treat this page as the running total you can glance at in the meantime.
Airport boards, metro timetables and prayer time tables are all printed in 24-hour form, which is why 17:09 is the version that matters when checking something against a screen or a printed sheet. This page shows 5:09 pm for everyday reading and 17:09 beside it, so the two never need converting in your head.
Common questions
What is 17:09 on a 12-hour clock?
The same instant is 5:09 pm in writing and nine minutes past five in the evening out loud. Anything from 13:00 onwards loses twelve to give the pm figure, which is the only sum involved in moving between the two.
Does the number update by itself?
Yes. It is recalculated every second from your device's clock, so nothing needs refreshing or restarting. Whatever is on screen is the current gap to 5:09 pm, not a figure worked out when the page first opened.
What happens once 5:09 pm has passed for today?
The count rolls over and carries on towards the same time tomorrow. That happens on its own at the moment the time passes — the page does not need reloading and there is nothing to reset by hand.
Which clock does the countdown use?
Your own. It reads the local time and time zone from the device in front of you, which in the Emirates means Gulf Standard Time, UTC+4. Travel and the count follows whatever the device picks up.