"Woman Laughing Alone With Salad" is a common stockphoto image, showing a woman (usually) by herself, (usually) laughing, smiling, or otherwise looking enrapt and joyous at the sight of a salad, of either the vegetable or fruit variety. As is common in stock photography, the woman tends to be attractive and affluent. As is also common with stock photography, because there are hundreds or thousands of versions of this image available, there are versions with men laughing at salads, groups of women laughing at salad, and if you really want to push the envelope, men and women eating salad together. Sometimes the woman might be making the salad, sometimes she might be consuming it. The important point is: woman, salad, positive emotions.
The ubiquity of the image has been noted for a long time, and knowyourmeme cataloged it a decade ago. There are many webpages exploring the phenomena. Someone has even written and performed a play about it. The image has obvious social connotations, since it suggests the idea that women should focus on "healthy eating" (and thus, of course, having the "right type of body") to the point that such nutritional goals cause pure ecstacy. But on the other point, when trying to generate excitement, how else to do it? Of course, there is "Frowning at Salad", but that is an entire other stock photo. The photographers have to communicate the idea that salad is good, and they do a good job of getting just the right pose and expression to communicate this idea in visual shorthand.
So while "Woman Alone Laughing At Salad" is silly, it no more silly than any other piece of stock photography and at least shows whimsy, instead of disappointment (which according to marketers, are the two female emotions).