You need to speak candidly in an interview.

Literal

Interview [at-では], frankly speak [nominalizer-こと] [subject-が] necessary is.

Another four-character compound, 虚心坦懐 — 虚心 ('open-heartedness') + 坦懐 ('frank, candid'). Meaning 'with an open and candid heart, straightforwardly.' A literary flourish appropriate in writing about attitudes or advice. こと-nominalization lets the predicate 必要 ('necessary') take the whole 'speaking candidly' clause as its subject.