Criminalization is the act of making something criminal, or making it against the law. When the U.S. Congress made it illegal to consume or sell alcohol in 1920, that criminalization of drinking ushered in a historic period known as Prohibition.
Any activity can be criminalized, or go through a process of criminalization. When Sleeping Beauty's parents banished shuttlecocks and spinning wheels from their fairy tale kingdom, that was the criminalization of spinning. The word can also apply more generally to not just to the outlawed activity, but to people or practices associated with it. Thus, a law making it a crime to eat candy might be called "the criminalization of Halloween." And crime or not, that's just wrong.