According to an embodiment of the present disclosure, provided is a method by which a first device performs SL communication. The method may comprise the steps of: generating S-SSB including symbols for S-PSS, symbols for S-SSS, and symbols for PSBCH; and transmitting the S-SSB to a second device, wherein a total number of symbols for S-PSS is three, and the symbols for S-PSS include a first S-PSS symbol, a second S-PSS symbol, and a third S-PSS symbol.