Final answer:
The figurative language used in the passage, where Jackie is described as the 'black sheep' of her family, functions as a metaphor which directly compares Jackie to something, suggesting she feels out of place without saying she is literally a sheep.
Step-by-step explanation:
The passage "Jackie always knew she was the black sheep in her family, so she moved across the country to live on her own terms." uses a metaphor as a device of figurative language. A metaphor is a direct comparison between two unlike things without using 'like' or 'as'. By describing Jackie as the 'black sheep', the author is not suggesting she is an actual sheep, but rather using the term to indicate that she feels different or out of place within her family. This is a common expression used to denote someone who is considered the odd one out in a group or community.