Hello All
I'm a new in SQL and in vba here is my code snippet , can someone explain me how emboldened part works? Why does it needs those to parameters (sql, con)
Thanks in advance

Dim da As OleDb.OleDbDataAdapter
        Dim sql As String = Nothing
        dbProvider = "PROVIDER=Microsoft.Jet.OLEDB.4.0;"
        TheDatabase = "/AddressBook.mdb"
        MyDocumentsFolder = Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
        FullDatabasePath = MyDocumentsFolder & TheDatabase
        dbSource = "Data Source  = " & FullDatabasePath
        con.ConnectionString = dbProvider & dbSource
        MessageBox.Show("Database is now open")
        sql = "SELECT * FROM tblContacts"
        da = New OleDb.OleDbDataAdapter(sql, con)
        da.Fill(ds, "AdressBook")
        MessageBox.Show("Database is now Closed")
        txtFirsName.Text = ds.Tables("AdressBook").Rows(0).Item(1)
        txtSureName.Text = ds.Tables("AdressBook").Rows(0).Item(2)