Pardon me for leaving (before you); a polite phrase used when leaving a workplace or group while others remain.
「お先に失礼します」と言ってオフィスを出た。
I said, 'Pardon me for leaving,' and left the office.
もうこれで失礼します。お先に失礼します。
I'll excuse myself now. Pardon me for leaving before you.
会議の途中で先に帰るときは、『お先に失礼します』と一言伝えるのが礼儀だ。
When leaving a meeting early, it is polite to say, 'Pardon me for leaving before you.'