It gives you a recipe for Vehemence Elixir, which you can craft at alchemist’s bench. The elixir gives you a specific temperature effect, depending on where you are when you consume it. If you’re in a hot area, it will lower your temperature. If you’re in a cold area, it will raise it.
However, be advised that the effect won’t change when you go from one area to another. So if you drink it in the volcano, it will cool you down. If you then take one of the exits from the volcano into the Frozen North, you’ll get frostbite.