Low poly means the minimum amount of geometry to display the desired amount of information at the desired viewing distance. Numbers mean basically nothing
"Lowpoly" is a catch-all term that generally refers to any models meant for use in realtime applications. The amount of triangles used is however many are needed to create a clean believable surface within the confines of the given technology. On modern games consoles you can have millions of triangles on screen at a time…
Yeah pratically the amount of polys ( better say tris ) are dictated by the technical limitations of the console or PC where the game will run. You usually take a look at your mesh from the distance that will be viewed at and you start removing polygons accordingly. I advise you to take a look at this table here to get a…