na-adjective
Refers to matters, property, or activities belonging to an individual rather than to a group, organization, or the public. Often used in contrast with 公的 (public, official).
私的な理由で会社を休んだ。
I took a day off work for personal reasons.
このメールは私的な内容なので、転送しないでください。
This email contains private content, so please do not forward it.