This is the 6585th most frequent Spanish word.
cartel
A poster or sign.
Here, 'cartel' is used to mean a physical sign or poster used for advertising purposes.
Vi un cartel en la calle que anuncia un concierto.
I saw a sign on the street advertising a concert.
In this instance, 'cartel' refers to a group or organization that works to control markets or activities, often with monopolistic intentions.
El cartel controla el comercio de ciertos productos en el país.
The cartel controls the trade of certain products in the country.
Here, 'carteles' means informational placards or labels, typically used to provide descriptions or captions, often in a museum or exhibition setting.