You can run a process starting at 4pm (16:00:00) and it will go to the activity Delay until time- (enter a time i.e 5PM (17:00:00)) and then at 17:00 the process will continue to work - so this could be used in a workflow whereby specific tasks are required to be completed by a certain time for the process to continue again.
The same thing with Delay Until Date Time - although the format is specific for DateTime.