A wireless access point is a networking device that allows you to easily connect to the Internet over the air. An access point is not a hotspot — it covers the area with a wireless signal, and that area that you can have your connection within, is called a hotspot.
An access point usually connects to a router via Ethernet as a standalone device, but it can also be built into a router. An AP can look a lot like a router, but there are more compact antenna-less designs too.