What does hotspot mean in a website?

Answer 1

An area of a graphics object, or a section of text, that activates a function when selected. Hot spots are particularly common in multimedia applications, where selecting a hot spot can make the application display a picture, run a video, or open a new window of information.

also it may be:

A specific geographic location in which an access point provides public wireless broadband network services to mobile visitors through a WLAN. Hotspots are often located in heavily populated places such as airports, train stations, libraries, marinas, conventions centers and hotels. Hotspots typically have a short range of access.

Answer 2

Could have several meanings but the one I am familiar with is what areas of a web page are being clicked on the most. There are tools available that can actually provide a "heatmap" comprised of different colors to indicate what areas are being clicked on the most. Deep red for a lot of clicks, cool blue for hardly clicked, etc...

NASDAQ use to have a heatmap on their website very similar to this. The days "hot" stocks were deep red, pretty hot stocks lighter shades of red, so for and so on.