It is describing a pseudovector (axial vector).

Direct answer

The statement
“ it is a vector having a straight line effect and reverses the sign when the coordinate axes are reversed ”
matches the defining behavior of a pseudovector , also called an axial vector. A classic example is angular momentum or magnetic field : they behave like vectors under rotations, but when you switch from a right‑handed to a left‑handed coordinate system, their components change sign, unlike an ordinary (polar) vector.

Quick Scoop

What the phrase is getting at

  • “Straight line effect” points to something that can be represented along a line in space, like an arrow, just as with ordinary vectors.
  • “Reverses the sign when the coordinate axes are reversed” is the distinctive transformation rule that separates pseudovectors from ordinary vectors.

In more advanced math/physics language, a pseudovector is an object that:

  • Transforms like a vector under proper rotations (turning the axes without flipping handedness).
  • Changes sign when you flip the coordinate system’s handedness (right‑handed to left‑handed), which is mathematically like reflecting all axes.

Polar vector vs pseudovector (table)

Here’s a compact view to compare:

Type Examples Behavior under axis flip
Polar vector Displacement, velocity, force Components keep their sign when the basis is inverted in the “pseudovector sense”; they are the ones that flip in the usual “coordinate reflection” picture.
Pseudovector (axial) Angular momentum, torque, magnetic field Components change sign when switching between right‑ and left‑handed coordinate systems.
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Mini story to remember it

Imagine you draw a spinning wheel and an arrow sticking out along its axis to represent its angular momentum. If you redraw the whole scene in a mirror, the wheel still spins the “same way” physically, but the axis arrow you use to represent that spin must flip direction to stay consistent with your new mirrored coordinate system. That “flip on mirror” is exactly the hallmark of a pseudovector.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.