Assuming for this example that the cell you want to monitor is A1, this
Worksheet Change event code should do what you want; it makes the
CommandButton (what you are using, right?) visible if and only if the value
in the cell is TRUE...

Private Sub Worksheet_Change(ByVal Target As Range)
If Target = Range("A1") Then CommandButton1.Visible = Target.Value = "True"
End Sub

This version makes the CommandButton visible is the cell contains **any**
entry...

Private Sub Worksheet_Change(ByVal Target As Range)
If Target = Range("A1") Then CommandButton1.Visible = Target.Value <> ""
End Sub

Rick