Displaying Calculated Hours using Text Label

Requirement: Display a calculated hours in Text Label

DefaultDate= 
If(SharePointForm1.Mode=FormMode.Edit || SharePointForm1.Mode=FormMode.View, ThisItem.'Travel start date', Today())

This logic is used in date datacard, if it is in edit mode take selected date or if it is in view mode take today’s date

DefaultDate=
If(SharePointForm1.Mode=FormMode.Edit || SharePointForm1.Mode=FormMode.View, ThisItem.'Travel end date', Today())

This is logic is used for date datacard, if it is in edit mode take selected date or if it is in view mode take today’s date

Text= 
If(DataCardValue4.SelectedDate = Blank() || DataCardValue5.SelectedDate =Blank(), "0", Concatenate(DateDiff(DataCardValue4, DataCardValue5,TimeUnit.Days) &", "&DateDiff(DataCardValue4,DataCardValue5,TimeUnit.Hours)&","&DateDiff(DataCardValue4, DataCardValue5,TimeUnit.Seconds)))

Now Click on Run button in power apps, add details as shown in below

Enter details in Power apps