"And, has thou slain the Jabberwock? Come to my arms, my beamish boy! O frabjous day! Callooh! Callay!" These lines express the narrator's excitement and pride after a young hero defeats the fearsome Jabberwock. The joyful exclamations like "Callooh! Callay!" highlight the celebration of the victory and the hero's bravery.

"He chortled in his joy." This indicates that the hero is delighted and triumphant about the successful slaying of the creature. The playful, nonsensical language captures a whimsical and fantastical mood, characteristic of Lewis Carroll's poem, emphasizing the fantastical journey and victorious ending.