leaving one's seat; temporarily stepping away from one's desk or seat (often used in meetings or as an auto-reply).
すみません、少し離席します。
Excuse me, I'll step away for a moment.
ただいま離席中です。折り返しお電話いたします。
Currently away from my desk. I will call you back.
会議中に長時間離席するのは避けてください。
Please avoid leaving the room for a long time during the meeting.