Present Circumstances are the minute to minute, beat by beat conditions under with which your character must contend to get what they want.
What’re your people having to deal with right here, right now? These are the objects, emotions, thoughts, people, bodily functions and surprises that stand between them and where they are fighting to get to—no matter what.
That sofa they hate, grief caught in the throat, self-doubt, a tight-fisted husband, a desperate need to pee, the kitchen ceiling falling in—these are all examples of the circumstances, the primordial sludge, out of which story emerges.
‘Story’ then can be seen as what happens when we convey to readers what happens when our people head bravely into (or flee quickly from) their immediate physical/psycho/emotional condition (present circumstances).
(hint: the easier it is to contend with/overcome, etc., the less interesting the tale.)