The raindrops were dancing happily on the window.

Meaning: This means that the raindrops that fell from the sky were moving in a way that made it seem like they were dancing happily on the window in the past.

Choice of Words: The is an article that is used to refer to a specific noun. Raindrops are the small drops of water that fall from the sky during rain. Were is a verb that is used to describe something that happened in the past. Dancing is a verb that means to move in a lively way, often with music. Happily means to be happy and cheerful. On is a preposition that means to be in or at a particular place or position. Window is the transparent opening in a wall or roof that allows light to enter a building. When you put them together, the sentence describes the raindrops that fell from the sky and moved in a happy and cheerful way on the window in the past.