Notice how the arrows on the mapping diagrams are paired with
the points on the graph of the functions.
You can move the point for $x$ on the mapping diagram to see how the function value for the functions change both on the diagram and on the graph.
The arrow on the point on the mapping diagram target axis indicates whether the value of the function is increasing (pointing up) or decreasing (pointing down).
Notice how the graph and mapping diagram visualize the fact that for the general trigonometric function has the same basic shape as core function though its period has changed to $2\pi/B$, extremes have changed to $\pm|A|$ for the sine and cosine.
Check the box to show points on the graph and arrows on the diagram
for the function $ f(x) =2\cdot trig(x-\pi/2)$.
Move the slider to change the function to $\cos$ or $\tan$ or the values of $A, B,$ or $C$ which you can also enter manually.