お先に失礼します (Osaki ni shitsurei shimasu) means "Excuse me for leaving first" or "I will be leaving now." You use this phrase when you are leaving a workplace or a gathering before others, showing respect and politeness to those who remain.

職場などで、他の人より先に帰る時に使う挨拶です。残っている人への配慮を示します。