CSS translateX(n) moves an element from its current position towards right(i.e, towards x-axis) but y-axis remains same from its current postion. You can compare image 1 and image 2 to see the differences.
Here Image 2 is moved towards 50px right but y-axis is remained same.
Image 2:
Here, in Image 2, Image moves 50 pixels to the right from its current position and y-axis is as it is.