Xīngqī’èr means “Tuesday”, xīngqīsān means “Wednesday”. In Chinese the days of the week are numbered: Tuesday is the second day of the week, Wednesday the third.
You see a calendar open at a week with seven days. In the top left corner a small picture advertises a ham whose bone sticks out as straight as the horizon: xīng. On the horizon stands a skier drinking tea: qī – also spoken with a level tone. Add the number you already know to xīngqī and you have the day of the week. That lets you say Monday to Saturday; only Sunday is an exception.