Juror #10 refers to the witness. Who supposedly saw the killing, and under what circumstances?

There are really two witnesses: "the old man" and "the lady across the street". The lady across the street claims she saw murder through her window. The 9th Juror calls into question the eyewitness testimony of the woman living across the street, as she wore glasses but chose not to wear them in court, calling into question whether or not she would have been wearing them in bed, when she saw the murder through her window.