It’s surprisingly hard to find these defined anywhere, so here they are.

SVN Letter Codes

U
Working file was updated
G
Changes on the repo were automatically merged into the working copy
M
Working copy is modified
C
This file conflicts with the version in the repo (see Conflicts below)

?
This file is not under version control
!
This file is under version control but is missing or incomplete

A
This file will be added to version control (after commit)
A +
This file will be moved (after commit)
D
This file will be deleted (after commit)

Source