Hello,
In PotPlayer, it's called simply "Jump to Previous/Next Subtitle", located in General->Shortcuts->Playback->Jump (to)->Previous Subtitle/Next Subtitle. It allows to jump from one subtitle's position to the next or previous. It's useful, for example, if you don't want to watch some scene in a movie and instead of jumping some fixed amount of seconds ahead, you jump right to the next dialog.... Or you can repeat the current actor's phrase, by using the "Previous" and "Next" shortcuts simultaneously....
sorry if bad english..