(noun)
a space that is unoccupied (vacant) and thus available, such as a residential accommodation, a hotel, an office, or some other property;
e.g. There is a vacancy in the apartment building, so you can apply to move in there.
(noun)
the state or quality of being empty, unoccupied, and vacant, or an instance of something being thus empty;
e.g. I checked the schedule for the room's vacancy before going inside.
(noun)
the quality of being empty-headed, lacking in understanding or intelligence, or generally mentally idle/inactive, or a state of physical idleness or relaxation;
e.g. We were surprised by his vacancy and foolishness in such everyday matters.