Classical entanglement occurs for instance when I know there is two balls in a box: a red one and a black one. If I take one ball from the box, then as soon as I see its color, I know what is the color of the other one still in the box.
1 - In the following situation, the two coordinates x and y of the particle are separable: if I measure y I don't know about x, i.e. I have no correlation between x and y.
2 - In the following one, coordinates x and y are entangled: if I measure y I know about x, x and y are correlated.
Geometrically both above situations look pretty much the same, it is just the orientation of the observer in the room which is different.
Entanglement is not a geometrically intrinsic property but something related to what we can observe in a specific configuration.
The more famous situation of two EPR particles, with entangled spins, is formally indentical, except that spin replaces the position:
Analogy in day to day life
If two people are called Bob, whenever I call "Bob!" they don't know who
I am calling.
Entanglement has something to do with language adequacy.
Defenders of hidden variables theory would argue that when two people are called Bob they are still two different persons, and I can distinguish them by other means.