It protects the people from falling from building.
Is there any single name for it?
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It's a Balustrade which means a row of balusters topped by a rail.
Baluster : an object or vertical member (such as the leg of a table, a round in a chair back, or the stem of a glass) having a vaselike or turned outline;
Synonymns : Railing, fence, rails, banister, bars etc.
It's a balustrade.
1 : a row of balusters topped by a rail 2 : a low parapet or barrier
It's a railing:
a barrier consisting of a rail and supports
Pictures are probably more valuable here though. Searching for "balcony railing" will return many relevant images, including this one:
Wikimedia Commons: Prague Praha 2014 Holmstad Beautiful railing on balcony at Mala Strana