Answer: It changes them from nouns to adjectives.
Explanation:
The definition of a noun is a word that names a person place thing or idea.
The words given "energy, athlete, and poet" are examples of nouns.
Adjectives describe qualities, characteristics, attitudes, etc.
by adding the affixes you get words that may describe. . .
Can you imagine an energetic athlete, an athletic poet (who floateted like a butterfly and stung like a bee- Muhammad Ali) or poetic energy?