See What F-Stop I Shot My Photo At?

Lightroom lists any information your camera embedded in your file over in the Metadata panel in the Library module’s right side Panels area. In the default view (chosen in the pop-up menu on the left side of the panel header), the information is in the bottom section and includes the f-stop and a whole bunch of other things, like your shutter speed, ISO, the lens you used, the make and model of your camera, whether your flash fired, what focal length you shot it at, the date and time you took the shot, and so on.