What does yellow ‘it’ indicate?

As they jostled their way through a crowd of confused Hufflepuffs, Harry suddenly grabbed Ron's arm.
"I've just thought -- Hermione."
"What about her?"
"She doesn't know about the troll."
Ron bit his lip.
"Oh, all right," he snapped. "But Percy'd better not see us."
Ducking down, they joined the Hufflepuffs going the other way, slipped down a deserted side corridor, and hurried off toward the girls' bathroom. They had just turned the corner when they heard quick footsteps behind them.
"Percy!" hissed Ron, pulling Harry behind a large stone griffin.
Peering around it, however, they saw not Percy but Snape. He crossed the corridor and disappeared from view.
"What's he doing?" Harry whispered. "Why isn't he down in the dungeons with the rest of the teachers?"
"Search me."

:What does yellow ‘it’ indicate?
(If ‘it’s is the stone griffin, what does the word ‘around’ imply?)