Long story short, it's the belief that there is a higher power of some kind directly related to the universe as a whole, but said being does not directly intervene in what happens (at least nothing we can tell, anyways). I;E, the, "God," of deism has very little in common with those of Abrahamic religions, due to the fact that it does not perform miracles, answer prayers, or what-have-you. Deism does not have a religious text like those of the Abrahamic religions either, largely due to the fact that Deism is a lot more of a belief than a religion.
That's the best I can explain it, anyways. Hopefully that helps!