If a fabric or product is classified as water-repellent it means it will repel water but is not impervious to it, or put in another way, there is a level of water pressure it can withstand before leaks start to appear.
Water-repellent jackets can prevent moisture and short rain showers getting through, as water molecules, due to the
impregnation of the outer fabric, evaporate and penetration of moisture is prevented, for example, by
wind or extreme pressure on the material. Regular impregnating of the material preserves the water-repellent qualities.