What happens to the props that I pass to a React Bootstrap component?

I am working on project at work, and I keep seeing objects and values passed as props to React-bootstrap components. How and where are these props handled? What happens when I pass some random prop to a React-bootstrap component? How can I know where and how is that prop handled?

<ButtonGroup size={bsSize}> 
  <Button {...props}>Left</Button>
  <Button disabled={disabled}>Middle</Button>
  <Button {...props}>Right</Button>
</ButtonGroup>