Figurative language adds meaning and interest beyond the merely literal to a written work. In "used the dipper to drink," the factual meaning is that Mattie took a drink of water. However, Anderson uses two figurative devices in this phrase to enliven the prose. The first is alliteration, which is when words beginning with the same consonant are placed close together. As we can see, "dipper" and "drink" both begin with the letter d. Second, Anderson uses imagery, description using the five senses of sight, sound, taste, touch, and smell. Saying "took a drink" would communicate what happened, but mentioning a dipper offers a visual image of how Mattie drank, highlighting the difference between her eighteenth-century culture and our own.
It can be difficult to convincingly pull literary devices (figurative language) from a snippet of a quote, but the entire passage is full of imagery and also uses alliteration, showing that Anderson was trying to both paint a picture and create a sense of rhythm with her use of language:
I drew a bucket of water from the well and used the dipper to drink as much as I could hold. I spilled the dipper over the top of my head, shivering as the cold water trickled down my back. I carried the bucket inside and poured a mug for Grandfather. He was already asleep by the time I entered his room. His color was better, and he was snoring like a barn full of plow horses. I set the mug on the floor and tiptoed back downstairs.
We note that Anderson uses sight, touch (shivering from the cold of the water), and sound (snoring) imagery in the passage to convey a full sense of the scene. We also notice that the "d" alliteration follows after the "w" alliteration of "water" and "well," bringing a rhythmic quality to the sentence.