Is 4cosx-1 a vertical or horizontal translation

If we have

y = 4cosx -1

This is the normal cosine graph with an amplitude of 4 that is shifted "down" one unit. Thus, the normal cosine graph is shifted "down' by one unit and "stretched" vertically.

Here are the graphs of y = cos x     and   y = 4cosx -1   https://www.desmos.com/calculator/fnvfsqgvgm

Note that the periods of the two functions are exactly the same, so there is no horizontal "stretching."