Translation:Are we going home?
Why is it sometimes DOMU and sometimes DOMA? What's the difference?
In direction "towards" home, homeward, it is the adverb domů https://en.wiktionary.org/wiki/dom%C5%AF#Adverb . At home is the adverb "doma" https://en.wiktionary.org/wiki/doma#Adverb . Where is he? Doma. Where is he going? Domů. In German wo vs. wohin / zu Hause vs. nach Hause.