Animals eat quickly.

Meaning: This means that the animals are eating their food quickly. It's like saying, The creatures are consuming their nourishment in a hurried way.

Choice of Words: Animals is a noun that refers to living creatures that are not human. Eat is a verb that means to consume food. Quickly is an adverb that means in a fast or hurried manner. When you put them together, "Animals eat quickly" is a sentence that describes animals consuming food in a fast manner.