In terms of train traffic routing (including many LRT systems, including Vancouver's Skytrain system), a 'falling point' refers to the section just before the opposing end of a train switch. You can think of it as a 'reverse switch' of sorts. (On the Vancouver Skytrain, the sign used for a switch is shaped in the form of a 'home base', that is, a triangle top with a square bottom. A 'falling point' marker is the same sign turned upside down)

For the most part, a falling point is used as a reference point when directing trains. When a train is asked to stop at a falling point, the most common reason is due to an oncoming train on the same track that will travel through the switch. After the oncoming train clears the switch, the switch is thrown, and the train stopped at the falling point is allowed to pass.

A falling point has the same name as its 'parent' switch. That is, you would say, "Falling point of switch 54"

Here's a diagram to help you out:

 SWITCH_|   |
     FP_|\  |
        | \ |_FP
        |  \|_SWITCH
        |   |