It began in a Woman's Club in London on a February afternoon-an uncomfortable club, and a miserable afternoon-when Mrs. Wilkin who had come down from Hampstead to shop and had lunched at her club, took up The Times from the table in the smoking-room, and runnir her listless eye down the Agony Column saw this:

To Those who Appreciate Wistaria and Sunshine. Small medieval Italian Castle on the shores of the Mediterranean to be Let furnished the month of April. Necessary servants remain. Z, Box 1000, The Times.
That was its conception; yet, as in the case of many another, the conceiver was unaware of it at the moment.
So entirely unaware was Mrs. Wilkins that her April for that year had then and there been settled for her that she dropped the newspap with a gesture that was both irritated and resigned, and went over to the window and stared drearily out at the dripping street.
Not for her were mediaeval castles, even those that are specially described as small. Not for her the shores in April of the Mediterranear and the wistaria and sunshine. Such delights were only for the rich.

How does the setting of the passage affect the reader's understanding of Mrs. Wilkins?

The setting of the passage affects the reader's understanding of Mrs. Wilkins by highlighting her feelings of resignation and envy. The uncomfortable club and miserable afternoon create a sense of gloom and hopelessness, which is further emphasized by the contrast between Mrs. Wilkins' mundane life and the luxurious Mediterranean castle described in the advertisement. This contrast serves to emphasize Mrs. Wilkins' feelings of envy and her sense of being excluded from the kind of life she desires.