Robin and Brook prevent Hody's men from reaching Shirahoshi. The anime specifically shows Robin using a new giant-limb technique to stomp out several attackers (Wiki). Anime vs. Manga Differences
While the episode follows the manga source material, it adds several extended scenes: One Piece Episode 556
An elaborated explanation of the by Franky (Fandom). Robin and Brook prevent Hody's men from reaching Shirahoshi