The figurative language used here is a simile. A simile is a figure of speech that compares two things. In this case, the student takes place of the sheep and the school takes place of the meadow. The student is trying to convey how out of place they are in the new school.
Notice how the word soliloquy is a bit like the word 'solo'. This is basically what it is: a solo in drama, where somebody is projecting their inner thoughts. This gives the audience direct access to the character's feelings.
