A hypothesis is what you would normally use in a science experiment. A hypothesis is an 'If', 'then' statement. Something like; IF you added milk THEN something would happen. Also its something than can not be tested. So; IF you add water to the plant THEN it will grow. Hope this helped.
A hypothesis does not have to be used in just a science experiment but you would use it a like a foundation for your research and actual experiment, it is your theory your guess of the outcome of the experiment it is not definite, and could at the end prove to be right