Their feelings and opinions are expressed through it. (if its active than change into passive voice if its passive than change into active voice)

It expresses their feelings and opinions.(passive to active)

Explanation:

Passive voice is described as the grammatical construction in which the object and action are being emphasized rather than the subject. The subject in such construction becomes the recipient of the action and is being acted upon by the verb/action. It is primarily employed to show interest in the object or verb instead of the subject. The given sentence is written in the passive voice as the object is being emphasized and the subject receives the action and to convert it into active voice the object would be replaced by the subject('It') to shift the emphasis.

i can you there : )

the underline word is basically like a prepositional phrase.