Horizontal Translations

Imagine you have a single point.

Then you take that point and move it horizontally (left or right) a certain number of units. In this case moving the point left 3 units.

Now picture doing that same movement to every single point on a graph. In this case it takes the entire curve and moves the curve left 3 units.

Remember there are an infinite number of points that make up the graph, only a few are shown with an arrow moving them, but all of them are moving.