The Sign Inside

A plus inside the brackets moves the graph left, which surprises most people at first. Take $y = f\left(x+2\right)$ with $f\left(x\right) = {x}^{2}$. The parent's lowest output comes when f receives 0. Here f receives $x+2$, and that is 0 when x is -2. So the vertex is at (-2, 0), two places left.

Follow one more point to see why. On the parent, input 2 gives 4: the point (2, 4). On the new graph, f must receive 2, so $x+2 = 2$ and x is 0. The point with height 4 is now (0, 4). The rule adds 2 to x before f sees it, so x has to be 2 smaller to feed f the same number, and smaller x means further left.

So do not guess from the sign. Ask where the inside of the brackets is 0: that is where the vertex goes. $f\left(x+2\right)$ is zero inside at -2, and $f\left(x-2\right)$ at 2.