Indeed, ? in SQS code is short for IF, and precedes a THEN (in SQS represented by a colon : ).
In triggers etc. the Condition field represents the IF portion (no extra question marks etc. needed) and the On Activation portion represents the following THEN code. Basically "if thing X is true, then do Y". With SQF, you can do more complicated things like "if thing X is true, then do Y, else do Z".
I suggest taking a peek at some of the newbie tutorials in scripting if you want to get into it - the ones for OFP are equally applicable for ArmA most of the time!
Wolfrug out.