Honorific verb meaning 'to come,' 'to go,' or 'to be' (somewhere), used for people of higher status or customers.
先生はもう教室にいらっしゃいますか。
Is the teacher already in the classroom?
どうぞお入りください。ゆっくりいらっしゃいませ。
Please come in. Welcome — take your time.
明日はお客様がたくさんいらっしゃいます。
Many guests will be coming tomorrow.
As an auxiliary (honorific), it indicates ongoing action or state — the honorific equivalent of 'to be (doing)'.
社長は会議室でお待ちになっていらっしゃいます。
The president is waiting in the conference room.
お客様は今、展示場をご覧になっていらっしゃいます。
The customers are currently looking around the exhibition hall.
何をしていらっしゃるんですか？ゆっくり話してください。
What are you doing? Please speak slowly.