Film lamination adds a layer of protective coating (usually a type of plastic film) adhered to the printed surface. This can be either gloss or matt and will also improve its sturdiness and water resistance.
Film lamination also has the added benefits of improving the tactile feel of the of the printed surface, lending it a smooth finish.
If a high gloss laminate is applied to the printed surface, photos and images appear to have more contrast and have better sharpness.
Matte laminated prints are more subdued but add a very luxurious and elegant finish to the printed surface.
Typically, lamination is used if sturdiness is required such as for soft covered books.