Mr. Ant, thanks for your hard work today too. Here, I'll give you a sugar cube.
Literal
Ant-[polite-さん], today [also-も] thanks-for-work-[polite-さん] is [よ]. Here, cube-sugar give [よ].
A whimsical, cutesy monologue directed at an ant. ~さん on アリ anthropomorphizes the insect. ご苦労さん is the casual form of ご苦労様 ('thanks for the hard work'), traditionally used downward (to subordinates, workers) — though the etiquette has blurred in modern usage. 角砂糖 ('corner sugar' = sugar cube) is a straightforward compound. The whole piece hinges on the speaker playing pretend with the ant.