Best book/resource on modern UI/UX

I am joining a new company, one primarily focused on UI/UX. My role will be on the backend and around infrastructure but since this is a core thing for them, I want to know more.

In particular, what is the best book/resource you would recommend for learning about modern UI/UX: principles, design methodology, practical tips?

It's important that it's not some foundational text from Bell Labs written in the 60s, although obviously nice if it mentioned a bit of history, but rather something focused on modern stuff, especially mobile apps. How is it actually done today.

Which technologies should I have at least cursory knowledge of, which tools are widely used, which are hip, and which are on the COBOL path? What is the modern approach to measuring and improving user experience?