This is a handbill (a printed advertising sheet) for Harry Philips' Living Mythological Mermaid exhibit.
Sideshows and exhibitions of curiosities have appeared in travelling fairs, circuses and taverns in England since the 1600s. Some of these curiosities were genuine - people born with abnormal features or those able perform extraordinary physical acts by contorting or misshaping their bodies - and some of them were fake - based on illusions and tricks. These shows were a particularly popular form of entertainment during the Victorian period.
These acts relied a great deal on shock, therefore performers were not revealed in the flesh to audiences until money had changed hands. Titillating advance publicity was crucial, and the people described in handbills and posters often bore little resemblance to what lay behind the curtain or turnstile. Exaggerated and stylised illustrations lent age to dwarf acts, stature to giants, and plausibility to mermaids and bear boys.