Scaling a business means finding ways to be more efficient, so that you make more money than you spend, as your grow.
For technology, this means building up our hardware and software systems, such that they can handle larger and larger loads. It also means refactoring our code, designing our systems in more efficient ways, and learning new tricks so that we can do more, with less.
As an application security professional, you will always be drastically outnumbered by software developers, operations personnel, and the rest of the IT department. Thus, to try to keep pace with them, we must scale.