you need to make you array function read the data into an array, process it and create an output array.
Then the array function nneeds to be entered in a multi-cell array formula (D3:D7) using ctrl-shift-enter.
Public Function MakesSound(AnimalName As Range) As Variant
Dim Ansa() As Variant
Dim vData As Variant
Dim j As Long
vData = AnimalName.Value2
ReDim Ansa(1 To UBound(vData), 1 To 1)
For j = 1 To UBound(vData)
Select Case vData(j, 1)
Case Is = "Duck"
Ansa(j, 1) = "Quack!"
Case Is = "Cow"
Ansa(j, 1) = "Moo!"
Case Is = "Bird"
Ansa(j, 1) = "Tweet!"
Case Is = "Sheep"
Ansa(j, 1) = "Ba-Ba-Ba!"
Case Is = "Dog"
Ansa(j, 1) = "Woof!"
Case Else
Ansa(j, 1) = "Eh?"
End Select
Next j
MakesSound = Ansa
End Function