According to Wikipedia ‘S/Z’ or ‘SZ’ may refer to:
the Alfa Romeo SZ
the NATO country code for Switzerland
the Suzuki sporadic group - a mathematical group
Slovenske železnice - the Slovenian railway company
Szöllősy - the catalogue of all the compositions of Béla Bartók
SZ cycle-car - a Soviet/Russian microcar series
the Sunyaev-Zel'dovich effect in astrophysics
the city of Shenzhen in Guangdong province in the People's Republic of China
Sprite Zero – the diet version of Sprite
S/Z - the structuralist analysis of Honoré de Balzac’s "Sarrasine", by Roland Barthes
etc.
It also refers to the collaborative practice of Zayne Armstrong and Sarah Elliott, initiated in 2007, based in Rotterdam and New York City