N2
いわゆる
What is called, So-called, Generally known
ハンバーガーやフライドポテトはいわゆるジャンクフードだ。
Hamburgers and French fries are so-called junk food.
Explanation
「いわゆる」 means 'so-called / what is commonly called'. It goes right before a noun to bring in a well-known nickname, jargon or catchword: 「いわゆる勝ち組」 (the so-called winners); 「いわゆるメタバース」 (what is called the metaverse). Sometimes the speaker only borrows the common name without agreeing with it. It can only stand before a noun, never as a predicate or adverb.
Mixed up with
In Chinese, 'so-called' often sounds sarcastic, but 「いわゆる」 is mostly neutral: it only means 'commonly called'. Don't read a negative tone into it.
In writing, the word after 「いわゆる」 is sometimes put in quotation marks for emphasis.