"아버지와 어머니는 부모입니다."
Translation:Fathers and mothers are parents.
Its a common contraction with the copula verb 이다. You take the noun and concatenate a conjugated form of 이다.
부모입니다 = 부모 ("parents") + 입니다 ("to be" in formal speech)
Contrast this with the negated version "are not parents": 부모가 아닙니다. Note that the noun gets tagged with the subject marker and the conjugated negative copula is its own word.
And interesting to note from the notes that: 부: father 모: mother * 부모: parents! (Makes total sense, very practical) But then what's the difference 부 vs 아버지 and 모 vs 어머니? Are 부/모 more a "biological" description while the others more "functional"? Or rather sino-korean vs Korean??