An adjective is a describing word, for example: Those colors are very bright.
Bright is the adjective, because its talking about the colors.
An adverb is a word or phrase that modifies the meaning of an adjective, verb, or other adverb, place, or time. For example: She kindly told told him to go away. Kindly is the adverb.
A preposition is a word that tells you where something is, for example: The puppy is on the floor. ON is the preposition.
Lastly, conjunctions are joining words, like: and, or but.
Hope it helps :)