UserForms are Initialized, not Labels and Listboxes. I would also create the entire process when the UserForm is displayed.
Try something like:
In a standard module, copy and paste:
Sub shwForm ()
UserForm1.Show
End Sub
Create a keyboard shortcut to call the show form macro, or attach it to a command button on the sheet.
Then, in Userform1's code module copy and paste this:
Private Sub UserForm_Initialize()
Dim x As Long, row As Long
Dim LastRow As Long
Dim countUnique As Integer
LastRow = 106
For x = LastRow To 1 Step -1
If Application.CountIf(Range("A:A"), Range("A" & x).Text) > 1 Then
Range("A" & x).EntireRow.Delete
End If
Next x
countUnique = Application.CountA(Range("A:A"))
UserForm1.Label1.Caption = countUnique
For row = 1 To 106
UserForm1.ListBox1. AddItem Sheets("Sheet1").Cells(row, 1)
Next row
End Sub
Note: you can also use the reserved word 'Me' when referring to controls on a userform, instead of having to key the entire user form name each time. So Userform1.ListBox1 and Me.ListBox1 both refer to the same object. Also, you can abbreviate Application.WorksheetFunction.CountIf to simply Application.CountIf
These shortcuts save a lot of keying when you have a multitude of userforms and worksheet functions coded in VBA.
Edit: it comes to mind that you did not state whether the 106 in your code represents the column of entries before or after the routine has been called. It would actually be better to adapt the code to account for 'variable' entries. Otherwise, you will be adding 'blank' entries in your listbox, if your beginning row count is 106.
This would be a better solution:
Private Sub UserForm_Initialize()
Dim x As Long, row As Long
Dim LastRow
Dim countUnique As Integer
LastRow = Sheets("Sheet1").Range("A" & Rows.Count).End(xlUp).row
For x = LastRow To 1 Step -1
If Application.CountIf(Range("A:A"), Range("A" & x).Text) > 1 Then
Range("A" & x).EntireRow.Delete
End If
Next x
countUnique = Application.CountA(Range("A:A"))
UserForm1.Label1.Caption = countUnique
LastRow = Sheets("Sheet1").Range("A" & Rows.Count).End(xlUp).row
For row = 1 To LastRow
UserForm1.ListBox1.AddItem Sheets("Sheet1").Cells(row, 1)
Next row
End Sub