The following code solved my problem:
Dim x As Integer = 16
lblRows2.Text = (From Rows In DataGridView1.Rows.Cast(Of DataGridViewRow)() Where Not Rows.IsNewRow AndAlso Rows.Cells(x).Value.ToString = "Dog").Count
This code means that the label will count how many the word "Dog" are in the column.
For the expert of the month, Sergey, your links didn't helped me. So 1 star will do it.