The picture shows
an anthropomorphic cat standing at a chalkboard, teaching other cats. On the chalkboard, there is a drawing and text that reads "FITS=SITS". The image has a vintage or retro feel, reminiscent of early 20th-century illustrations. The cat wearing glasses gives
an impression of sophistication or intellectualism. The setting appears to be a classroom or
lecture hall where the cat is giving a lesson. The term "fit" can refer to clothing size, and this joke implies that cats don't wear clothes, hence they are not concerned with what fits them because they sit on things rather than wearing them.