I am using this line in the script to filter all rows with the status Approved.
Set Field[tblHours::Status; "Approved"]
Now I want to display all rows with both "Approved" and "On hold". How do I achieve this?
Set field just modifies data in a field. How then do you use this data once set field has modified the field?
Is this a match field in a relationship or are you specifying criteria for a find?
Which method you are using then determines what to do with Set Field.
If this is a match field:
Set Field[tblHours::Status; List ( "Approved" ; "On Hold" ) ]
If you are performing a Find:
Enter Find Mode 
Set Field[tblHours::Status; "On Hold"]
Perform Find 
My apologies for not specifying it was in Find mode. Your answer worked like a charm! Thank you!
Retrieving data ...