The phrase "When you build in silence" implies that when you work on your goals, dreams, or projects without broadcasting them to the world, you maintain a level of secrecy or privacy. This can be a strategic approach.
The quote suggests that "People don't know what to attack" when your efforts are not readily visible or shared publicly. It implies that by avoiding unnecessary attention, criticism, or interference, you can work more effectively and protect your ambitions from external scrutiny or negativity.
In essence, this quote encourages a more private and focused approach to achieving your goals. It underscores the idea that sometimes, keeping your intentions and progress to yourself can be a wise strategy to safeguard your work and minimize distractions or potential obstacles from others.