A junction, in the context of rail transport

Rail transport

Rail transport is a means of conveyance of passengers and goods by way of wheeled vehicles running on rail tracks. In contrast to road transport, where vehicles merely run on a prepared surface, rail vehicles are also directionally guided by the tracks they run on...

, is a place at which two or more rail routes converge or diverge.
This implies a physical connection between the tracks of the two routes (assuming they are of the same gauge), 'points' (US: switch

Railroad switch

A railroad switch, turnout or [set of] points is a mechanical installation enabling railway trains to be guided from one track to another at a railway junction....

es) and signalling

Railway signalling

Railway signalling is a system used to control railway traffic safely, essentially to prevent trains from colliding. Being guided by fixed rails, trains are uniquely susceptible to collision; furthermore, trains cannot stop quickly, and frequently operate at speeds that do not enable them to stop...

.

one or two tracks each meet at a junction, a fairly simple layout of tracks suffices to allow trains to transfer from one route
to the other.