Final answer:
The symbol |<----->| stands for a double-sided arrow line, used in mathematics to denote a line extending infinitely in both directions, such as in vectors or number lines.
Step-by-step explanation:
The symbol |<----->| represents a double-sided arrow line. This is commonly used in mathematics to denote a line that extends infinitely in both directions. In the coordinate system, a double-sided arrow line can represent all the points along a straight path that extends without end to the left and to the right.
For instance, when discussing vectors in physics, a double-sided arrow could represent a vector with no specific starting or ending point, implying the direction and magnitude of a vectorial quantity. As another example, in the context of number lines, the double-sided arrow illustrates the idea that the line continues indefinitely in both the positive and negative directions.