Recap: A Gantt chart is made up of task bars, one for each of the tasks required to complete the project in hand.
The task bars typically have start and finish dates and therefore have different lengths on duration.
AND means both conditions within the brackets must apply.
The $ sign before a letter means keep that column fixed when applying the rule to the range of cells.
This formula gives you both the date and time in the same cell (i.e.