React is the most popular javascript library for building user interfaces. It is fast, flexible and it also has a strong community sitting online to help you every time. The coolest thing about React is its based on components, you break down your complex code into individual pieces i.e components and that helps developers in organizing their code in a better way. A lot of companies are moving to React and thats the reason most of the beginners and experienced developers also expanding their knowledge learning this library.
Props is simply shorthand for properties. Props are how components talk to each other and the data flow is immutable. Props are passed down the component tree from parent to children and vice versa.