I have been reading the book Fearless Symmetry by Ash and Gross.It talks about Langlands program, which it says is the conjecture that there is a correspondence between any Galois representation coming from the etale cohomology of a Z-variety and an appropriate generalization of a modular form, called an “automorphic representation".
Even though it appears to be interesting, I would like to know that are there any important immediate consequences of the Langlands program in number theory or any other field. Why exactly are the mathematicians so excited about this?