You would have to do that with a macro, or macros. Here is how I would do it.
First, enter 'UP' (no quotes) in cell X1 and hide column X.
Open Excel and show the Drawing toolbar. Click AutoShapes and select 'Block Arrows'. Select the up arrow in row 1 of the Block Arrows and click and drag on onto the worksheet and size and position it as desired. The object name should display as AutoShape 1 just below the Font name in the upper left corner. If it is not AutoShape 1, then make note of what it is named.
Next, if your trigger cell is not A1, then modify the macros below. Replace all "A" references with your cell reference, i.e. "F3", "H2", etc. If your arrow is not named "AutoShape 1" then replace all references in all macros to your shape reference, i.e. "AutoShape 2". Then copy these macros to the clipboard:
'=========
Public tAddr
Sub SetArrow()
tAddr = ActiveCell.Address
If Range("A1").Value > 0 And Range("X1").Value = "UP" Then
Exit Sub
ElseIf Range("A1").Value > 0 And Range("X1").Value = "DOWN" Then
SetGreen
ElseIf Range("A1").Value < 0 And Range("X1").Value = "DOWN" Then
Exit Sub
ElseIf Range("A1").Value < 0 And Range("X1").Value = "UP" Then
SetRed
End If
Range(tAddr).Select
End Sub
Sub SetGreen()
ActiveSheet.Shapes("AutoShape 1").Select
Selection.ShapeRange. IncrementRotation 180#
Selection.ShapeRange. Fill.ForeColor.SchemeColor = 17
Selection.ShapeRange. Fill.Visible = msoTrue
Selection.ShapeRange. Fill.Solid
Range("X1").Value = "UP"
End Sub
Sub SetRed()
ActiveSheet.Shapes("AutoShape 1").Select
Selection.ShapeRange. IncrementRotation 180#
Selection.ShapeRange. Fill.ForeColor.SchemeColor = 10
Selection.ShapeRange. Fill.Visible = msoTrue
Selection.ShapeRange. Fill.Solid
Range("X1").Value = "DOWN"
End Sub
'========
Press ALT + F11
In the menus at the top of the VBE, select INSERT > MODULE
Paste all three macros into the module editing area to the right.
Close the VBE and return to Excel.
Copy these macros to the clipboard:
Private Sub Worksheet_Change(ByVal Target As Range)
SetArrow
End Sub
Private Sub Worksheet_Activate()
ActiveSheet.Shapes("AutoShape 1").Visible = True
End Sub
Select the worksheet that your arrow is in and right click the sheet tab.
Select 'View Code'.
Paste the macro into the sheet module editing area to the right.
Close the VBE and return to Excel.
Since the arrow is already facing up, enter a positive number in your trigger cell. The arrow will turn Green. Enter a negative number in your trigger cell and the arrow will turn red and face down. Enter a positive number in your cell and it will turn green and face up.