If you want to display countdown timer for opening hours, please follow the following steps:

Enable the countdown in frontend by checking the Open Countdown option in the Views tab:

Modify the countdown message

To modify the default message, go to Messages and in the Open countdown section, update the message.

There is a [time] parameter that can be used to output the time.

Defualt message is We are opening in [time]. Please check back later.

Modify the countdown time format

To modify the time format, go to Layouts and update Countdown time format option. Defualt format is HH[h]:mm[m]:ss[s]