na-adjective
Used to describe a stance, answer, or attitude that agrees with or supports something. Often paired with 意見, 返事, or 態度.
彼はその提案に肯定的な意見を述べた。
He expressed an affirmative opinion on the proposal.
アンケートの結果
The survey results were mostly positive.
肯定 is the noun 'affirmation'; 肯定的 is the adjectival form used to modify nouns or as a predicate with だ/です.
Formed from 肯定 (affirmation) + 的 (adjectival suffix).