What does this even mean in English?
The Indonesian sentence means something like "His letter is not valid here".
Because "-nya" is makes it possessive. "Suratnya" is "His/her letter". "Surat itu" would be "That letter".
I am very confused by this question/answer does surat have a broader meaning than "letter" does it mean official document or similar?? or is the confusion about the use of the word apply ?? My only understanding of "does not apply here" would be about some kind of rule or law ? eg " Australian law does not apply here"