In The Lord of the Rings: The Two TowersThe Lord of the Rings: The Two Towers, at Helm's DeepHelm's Deep when AragornAragorn was commanding the Elves in Elvish language during the battle, he yell's
"Ladders"
yells "Ladders" in the Elvish tongue (Sindarin). A moment after thatlater we hear Gimli saying -
"Good"
"Good", because he was very eager to fight them, and finally the wait was over.
But how did he know what AragornAragorn said? How did he know Elvish?