The term promotion means different things to different people, but the simple understanding is doing whatever it takes to get your book the attention it deserves!
The truth is you’re a marketer from the moment you decide to write your book. You need to think like a marketer even as you select your genre and your book. As you get near to your publishing date there are marketing actions you or your publisher can take (reviews, preorders, and more). But over 16 years in the writing business has taught me that marketing locally is a must.
Book signing is still valid. It is still hard to get into stores, especially chains. Not because of bias, although that still exists, but with chains you often have to contact the corporate office and get approved. That said, if you are an author it is still worth your while.