자체 means itself, oneself, or one's own body (자: self, 체: body) 자체가 is 자체 + 가, where 가 is a particle indicating the pro/noun before it is the subject. 자체가 usage examples: - 집 자체가 낡았다: The house itself is decrepit. - 계획 자체가 문제투성이다: The plan itself is full of problems. Other 자체 examples: - 그녀는 건강 그 자체였다: She was the picture of health. - 그는 그녀의 신원 자체를 의심했다: He suspected her identity itself.

자체 in English just like ' itself ',we can understand as " in fact". and 가 has no meaning. it's a auxiliary word. in korean, we add 이 or 가 to the subject or the words you want to emphasize. if we use it in a sentence we can say " something 자체가 (a clause or adjective to describe the thing) ". it means that actually something is ……（just like you describe)