* It's a typo or abbreviation specific to a particular institution: A very small, specialized college or university might use a non-standard abbreviation internally.
* It's a colloquialism or informal term: The term might be used informally within a specific community or organization.
* It refers to a specific program or certificate: Perhaps it's a shortened version of a program name, like "Software Journalism" (though unlikely, as that's not a common field).
If you encountered "SJ" in relation to a degree, providing more context (where you saw it, the institution's name, etc.) would help determine its meaning.