Wiktionary
s.o.
abbr. 1 (context informal English) significant other 2 (context chiefly grammar and lexicography English) someone
Wikipedia
S.O. (rapper)
Oluwaseun Oluwatosin Otukpe (born 5 December 1988) who goes by the stage name S.O. or Seun Otukpe in full, is a Nigerian Christian hip hop musician, based in London, United Kingdom. So It Begins was released independently in 2011. Lamp Mode Recordings released his first studio album So It Continues in 2012, and this album would be his breakthrough release on the Billboard charts.