斟酒 is a verb-object compound meaning 'to pour wine/liquor for someone', commonly used in social drinking situations like business dinners or family gatherings. It is a separable verb (离合词): you can insert measure words, aspects, or objects between the two characters, e.g., 斟了一杯酒 ('poured a glass of wine'). The action is often performed by the host or a junior person showing respect to elders or guests.