Hi,
An AirPrint printer is a model supporting the AirPrint technology. Printers listed in the article About AirPrint - Apple Support are supported, but a printer manufacturer may have other AirPrint models as well. AirPrint means that printing is possible without extra software, provided that the printer and the iPhone are connected to the same network (Wi-Fi router). Not all apps support AirPrint, though.
AirPrint works with iPads and macOS computers, too.
Which exact printer make and model do you have?
In some cases, it may also be possible to print from an iPhone to a non-AirPrint (wireless) printer if a special app from the printer manufacturer is available.
Use AirPrint to print from your iPhone, iPad, or iPod touch - Apple Support