What does 一 + verb/noun + 一 + verb/noun mean?
In this particular example 一步一步 basically means "step by step"; it emphasizes how it's gradual and slow.  More generally it means "little by little", and the repeated character indicates what is occurring gradually.


  Aside from just meaning "one by one," when 一 (yī) is used with a measure word that is a unit of time like "day" or "year," the meaning changes to "little by little" ("day by day," "year by year") or "gradually."
  Expressing "one by one" with "yi": Used as "Little by Little", Chinese Grammar Wiki


I found the relevant passage from 活着 and it's:


  凤霞走后，有庆不干了。起先凤霞被人领走时，有庆瞪着眼睛还不知道出了什么事，直到凤霞走远了，他才挠着头一步一步往回走。我看到他朝我这里张望几下，就是不过来问我。他还在家珍肚子里时我就打过他，他看到我怕。


Here's my rough, somewhat literal translation:


  After Feng Xia left, Youqing stopped.  At first, when Feng Xia was taken away, Youqing's open eyes didn't know what happened, and when Feng Xia was far away, only then he scratched his head and step-by-step walked back.  I saw him face me here peering for a bit, but did not come over and ask me.  When he was still in Jiazhen's tummy I beat him, and he saw my fear.


And a professional translation:


  After Fengxia left, Youqing stopped listening to us.  When Fengxia was taken away, Youqing just watched, not knowing what was going on.  Only after Fengxia had gotten far away did Youqing scratch his head and slowly make his way home.  I saw him looking over at me a few times, but he didn't come over to ask what was going on.  When he was still in Jiazhen's stomach I had hit him, so he was scared of me.
  To Live: A Novel, Yu Hua, translated by Michael Berry