Science is knowledge.
The practice of science is nothing more, and nothing less, than the earnest and thoughtful work of figuring things out, of trying to understand, of learning how things work.
Scientists are people committed to this practice, or to a community of shared practice. They work together to understand. And understanding is a thing of immense power. If you understand why the car has stalled, for example, you can fix it. And if you know when the tide will ebb, you can escape the harbor.