Starting point
Option Explicit
Sub TranslateEngFr2()
Dim rEngFr As Range, rEng As Range, r As Range, r2, InputRng As Range
Dim iEng As Long
Dim MyAdd As String, xTitleId As String
Dim oDic As Object
Application.ScreenUpdating = False
Set oDic = CreateObject("Scripting.Dictionary")
oDic.CompareMode = vbTextCompare
Set InputRng = Application.Selection
'commented out for testing
' Set rEng = Application.InputBox("Convert Which text :", xTitleId, Type:=8)
' Set rEngFr = Application.InputBox("translation dictionary ", xTitleId, InputRng.Address, Type:=8)
'added for testing
Set rEng = ActiveSheet.Cells(1, 1).CurrentRegion
Set rEngFr = ActiveSheet.Cells(1, 3).CurrentRegion
For Each r In rEngFr.Rows
On Error Resume Next
'Eng is the key, Fr is the data
oDic.Add r.Cells(1, 1).Value, r.Cells(1, 2).Value
On Error GoTo 0
Next
For Each r In rEng.Cells
If oDic.exists(r.Value) Then
r.Value = oDic(r.Value)
r.Interior.Color = vbGreen
End If
Next
Application.ScreenUpdating = True
End Sub