Find and Replace multiple values over multiple excel files, using a script/VBA/Macro

Here you go:

Sub ReplaceInFolder()
    ' ************** Change the constants as needed ***************
    Const ListSheet = "List" ' sheet with the find and replace text
    Const FindCol = "A"      ' column with the find text
    Const ReplaceCol = "B"   ' column with the replacement text
    Const FirstRow = 2       ' first row with find/replacement text
    ' *************************************************************

    Dim wshList As Worksheet
    Dim r As Long
    Dim LastRow As Long
    Dim strPath As String
    Dim strFile As String
    Dim wbk As Workbook
    Dim wsh As Worksheet
    Dim strFind As String
    Dim strReplace As String

    With Application.FileDialog(msoFileDialogFolderPicker)
        If .Show Then
            strPath = .SelectedItems(1)
        Else
            MsgBox "No folder selected!", vbExclamation
            Exit Sub
        End If
    End With
    If Right(strPath, 1) <> "\" Then
        strPath = strPath & "\"
    End If

    Application.ScreenUpdating = False
    ' Set reference to the sheet with the find and replace text
    Set wshList = ThisWorkbook.Worksheets(ListSheet)
    ' Determine the last used row in the column with the find text
    LastRow = wshList.Cells(wshList.Rows.Count, FindCol).End(xlUp).Row

    strFile = Dir(strPath & "*.xls*")
    ' Loop through the workbooks
    Do While strFile <> ""
        ' Open workbook
        Set wbk = Workbooks.Open(Filename:=strPath & strFile, AddToMRU:=False)
        ' Loop through the worksheets
        For Each wsh In wbk.Worksheets
            ' Loop through the rows with find and replace text
            For r = FirstRow To LastRow
                strFind = wshList.Cells(r, FindCol).Value
                strReplace = wshList.Cells(r, ReplaceCol).Value
                ' Replace
                wsh.Cells.Replace What:=strFind, Replacement:=strReplace, _
                    LookAt:=xlWhole, MatchCase:=False
            Next r
        Next wsh
        ' Close and save workbook
        wbk.Close SaveChanges:=True
        strFile = Dir
    Loop
    Application.ScreenUpdating = True
End Sub