Okay, let's imagine that you are trying to write a really pretty and special story or poem. Now, imagine that you want to make it sound extra special by using words that are not very commonly used in everyday talk. This is called "poetic diction" - it means using words that sound very beautiful and elegant but are not very common in everyday language.
For example, instead of saying "the flowers looked pretty", you might say "the blooming flora looked resplendent". You might not use the word "resplendent" in everyday conversation, but in a poem, it sounds lovely and special.
People use poetic diction to make their writing sound more fancy and beautiful. But when we talk to our friends or family, we usually use more common words so they can understand us better. Just like we talk to a baby - we use words that are easy for them to understand.
So, poetic diction is like using big, fancy words to make our writing sound special and beautiful, but in everyday life, we use simpler words to communicate with our friends and family.