A Balustrade is a small fence or a tiny wall that one can find on for example a balcony. The term Balustrades can be multiple balustrades. One can also find balustrades on stairs. They're located on the outside of a stairway.

at the bowling alley i decided to put the balustrades up

alcove means: is an architectural term for a recess in a room, usually screened off by pillars, balustrades or drapery.

A railing at the side of a staircase or balcony to prevent people from falling.

balusters are the supports to the hand rail in stairs while a balustrade/banister include the handrail and balusters in stairs.