My read (and from what I know of ECS) is that it's basically claiming a system which automatically organizes the memory layouts of instances of different types of "entities" (i.e. "type" meaning which "components" it includes) in an efficient manner.

Here, an "entity" is just an object identifier (integer, or whatever). A "component" is a specific set of data relevant to some function (e.g. position component would have x, y, z floats, while damage level component might be a single float to represent amount of damage).

ECS generally means laying out all memory for all instances of a given component contiguously, so in the example I gave you'd have one array for all position components in your game world, and one array for all damage level components. The "entities" are just collections of these components from these different arrays. So the "player" entity for example is logically composed of one particular element of the position array and one particular element of the damage array. This is more cache friendly when you have a "system" (say, the physics subsystem) which generally only operates on one or a limited set of types of components across many entities.

There is no way ECS in general is patentable but their system which intelligently and automatically performs the memory layouting for their form of ECS (which also includes the notion of chunking these arrays into finite sized blocks) very well might be.