Yes, it separates the Pantone colour out almost like another layer.

When you usually send something to print, it gets converted into four colour layers—cyan, magenta, yellow and black. These become individual printing plates (or toner/ink layers in digital print), and mix together using dots at different densities to achieve the colours you used in your file.

If you use a Pantone colour, it’ll be converted into its own layer/plate, and printed using the selected Pantone formulation. This will be noticeable next to a CMYK mix because it’ll be a nice flat colour, while the CMYK mix will be made up of patterns of dots from each component colour.

edit: you don’t actually need to specify Pantone colours to do this either. You can simply set a colour as a spot colour and it’ll appear as its own plate (also known in software as a separation) for the press.