The meaning behind his words is obvious. After ten minutes if she isn't done he'll definitely go into the room to oversee the treatment.
Snow didn't say anything when she heard those words. That's because it's more than enough time for her to dress up the wound on Mo Ling's hand.
The reason she asked him to wait outside is to avoid the secret of Mo Ling's gender being exposed.
After Snow closed the door, Bi Yuhan stood leaning against the wall and lowered his head.
The air of gloominess which formed because of his impure feelings towards the boy around him dispersed at this moment.
That's because he came to a decision. A decision which he didn't dare to make before for fear of hurting the boy.
But the moment when he saw that knife aiming towards the boy's heart, he knew.. he knew that he can't be without him.
And when he saw the blood and that pale face, it's as if he'd rather be the one that's going through the pain.