What is the citizen's arrest law at the heart of the trial over Ahmaud Arbery's death?

As jury selection continues for the trial of three white men charged with the murder of Ahmaud Arbery in Brunswick, Ga. last year, one particular law is expected to become a focal point. Arbery, a 25-year-old Black man, was shot while jogging.

source https://www.npr.org/2021/10/26/1048398618/what-is-the-citizens-arrest-law-in-the-trial-over-ahmaud-arberys-death