Hi Mariusz Jakoniuk,
Thanks for using Syncfusion product.
You can able to get the location of the cell by using the TableControl.GetCellRectangle method. Please find the below code snippet,
Rectangle rect = this.sfDataGrid1.TableControl.GetCellRectangle(5, 2, false);
Point screenPoint = this.sfDataGrid1.PointToScreen(new Point(rect.Left, rect.Top));
And also you can refer the below documentation link to get the screen point for the given cell below,
Let us know whether this helps also if you need any further assistance on this.