What is voice?
"Voice" is the seal that marks your manuscript uniquely yours. You can also call it "style," because it's infused with your own unique personality. No one else writes quite like you, and no one ever will. If you have a strong voice, your writing will shine. The dialogue, action, plot, and pacing come together in a confident blend that stands out from the pack. A strong voice sells books. It gives the reader a special connection to your story, as if it's being told by a person, rather than through ink and paper.
How do I get "voice?"
Aye, there's the rub. You can't "get" it - only improve it. You already have voice - it's as much a part of you as the way you talk or act. What you need to work on is craft. Streamlining your work, and polishing your writing skills, will help your voice shine through. A reader won't see the mechanics of the work, then, but the way you tell the story. If they like your voice, they'll seek out more of your work. (If they don't, don't be offended. Opinions vary widely, and your voice may not be the type that reader can connect with. But someone will!) The more you improve your craft, the better your voice will get.