Can air travel through glass?

No.

But but heat can travel through glass. And so, in winter, for example, when the air outside is very cold, the heat from the inside air will travel out through the glass of a window.

Then this suddenly cooled air will be heavier than the surrounding air, and mvoe down the window. when it gets to the window's edge or the window sill, it willdeflect out into the room, creating a slight movement of air that we can interpret as a breeze. So it can FEEL as if cold air were coming in through the glass itself.