A water-resistant material is the one that resists water penetration to an extent, but it will not protect it completely. While a waterproof material is the one that can be submerged in water without being damaged for a certain amount of time.
Leather is a natural and porous material and therefore it is classified as Water Resistant. This means it will be perfectly protected in mild/small rain shower but too much water exposure can make it wet. In case your leather apparel gets little wet, use a soft cloth to wipe off but do not rub heavily. A little application of good quality conditioner and protective spray can provide some extra protection to water. Use of microfiber is not recommended. In an event that your leather garment does get wet, leave the garment to dry naturally.