Describes something related to a specific person, as opposed to a group or public matter. Often used for opinions, matters, or belongings.
This is my personal opinion.
個人的な問題で会社を休みました。
I took a day off work for a personal matter.
Personally, I don't think this movie is very interesting.
That's a personal matter, so it doesn't concern other people.
He quit the company for personal reasons.
I contacted him personally about the work.