"Meh" is an interjection used as an expression of indifference or boredom. It may also mean "be it as it may". It is often regarded as a verbal shrug of the shoulders. The use of the term "meh" shows that the speaker is apathetic, uninterested, or indifferent to the question or subject at hand. It is occasionally used as an adjective, meaning something is mediocre or unremarkable.
This example leads to another key aspect of boredom. As Eastwood, Frischen, Fenske, and Smilek point out, bored people become aware of their difficulty concentrating. As a result, bored people often try to amuse themselves by daydreaming and letting their mind wander. Interestingly, while mind wandering helps people to keep their minds occupied, studies suggest that the more your mind wanders, the more bored you feel. The idea is that you recognize that this daydreaming is meant to occupy your mind, and so you realize that the situation is boring.
There was also a piano, well littered with music, a sewing bag thrown down upon a cretonned window seat, and the generous fireplace was flanked by two huge baskets, one heaped with magazines, the other a perfectly round mound of yellow fur, which suddenly took form and life as a yellow tabby cat fastened hopeful topaz eyes upon them, blinked away a brief disappointment, and then yawned with ennui.