作为【zuòwéi】

作为 + noun means "as, in the capacity of". It names the role someone is speaking or acting in, and usually comes at the start of the sentence. The 为 is read wéi here, as in 认为. The register is neutral to formal.

The role belongs to the subject

The person or thing that fills the role is the subject of the main clause. When it isn't, the sentence says something odd.

• × 作为学生，学校应该帮助我们 → 学校应该帮助学生

In the wrong line, the school ends up being the student. If 作为学生 stays, the clause after it needs the students as its subject: 作为学生，我们应该好好学习.

Treat as, use as

With 把, or as the main verb, 作为 means "to take as, to use as".

In speech, 当 does the same job more casually: 把我当朋友 "treat me as a friend".