Hi there! I havent watched this series, but if you 'choke someone out', this generally means that someone was placed in a chokehold, with either an arm or hands around their throat in order to make them pass out. From the voice clip, I presume the action didn't get that far, and that the person was interrupted, but I haven't seen the series. Hope that helps!

Here is an image of a "choke out": https://www.dreamstime.com/tap-out-due-rear-naked-choke-female-fighter-choking-her-opponent-neck-who-tapping-out-defeat-jiu-jitsu-mixed-martial-image127372632