Hypothesis is a scientific way of answering a problem.
Hypothesis at some point is said to be "an intelligent guess". Let's say for example that you're conducting an experiment (The effect of rotten leaves as a fertilizer to the production of tomatoes). You haven't started on the problem yet, but you somehow expect the result to be (either a) the rotten leaves has no effect; or b) the greater the mass of the rotten leaves used as fertilizer, the greater is the production of tomatoes) But it's not just a "guess". Because it is "an intelligent guess". There is a reason behind why you came up with that guess.