な国民だ

are a ... people

→ だ
phrase Rare #20,642
are a ... people Used after a な-adjective to describe a nation's people, as in 民主的な国民だ (are a democratic people). The final だ is the plain copula; it may become です in polite speech.
JA: カナダ人は親切な国民だ。
EN: Canadians are a kind people.

イギリス人は実際的な国民だと言われている

The British are said to be a practical people.

イギリス人は実際的な国民だ

The British are a practical people.

私たちは保守的な国民だ

We are a conservative people.

日本人は勤勉な国民だ

The Japanese are a hardworking people.