It is steam, like from a teakettle. It freezes, or gets colder. It gets hotter. In all three forms, the molecules move. You could look at a glass of water all day and not see anything moving, but there is movement going on.
Molecules move all the time, but sometimes more than other.
The molecules in ice are similar to you and your classmates at school when you are working at your desks. You are moving a little but not much and you are staying in a certain arrangement of your desks. Molecules in solids also vibrate or move just a little. Liquids are more like when the bell rings and you and your friends head out into the hall. You are all packed pretty close together, but you are moving more than when you were sitting at your desks.