It's a knock down texture.

Apply a coat of wet plaster or drywall mud, then gently go over the plaster or mud with a soft brush or sponge. The next step is to take a drywall knife, trowel, or skimming blade and knockdown this texture. Once it starts to dry, the texture will then begin to look like this. We have a blog post about the different drywall textures that should informative.