For Each row As DataGridViewRow In DataGridView1.Rows
Dim day As String = row.Cells("DayColumn").Value.ToString()
Select Case day
Case "Sunday"
row.Cells("DayColumn").Value = "الأحد"
Case "Monday"
row.Cells("DayColumn").Value = "الاثنين"
Case "Tuesday"
row.Cells("DayColumn").Value = "الثلاثاء"
Case "Wednesday"
row.Cells("DayColumn").Value = "الأربعاء"
Case "Thursday"
row.Cells("DayColumn").Value = "الخميس"
Case "Friday"
row.Cells("DayColumn").Value = "الجمعة"
Case "Saturday"
row.Cells("DayColumn").Value = "السبت"
End Select
Next