"Our mother's sister's husband is our mother's brother-in-law."
Translation:'IrneHnalma' ghaH SoSma' be'nI' loDnal'e'.
A quick comment to the course creators: It took me a while to get my head around this sentence. At least in my mind, the husbands of my mother's sisters are my "uncles", not my "mother's brothers-in-law". For that reason, it didn't occur to me to try to translate "mother's brother-in-law" as 'IrneHnal, but rather as SoS loDnI'nal or SoS loD'e'nal or something like that.
I would consider changing the "default" English sentence to "Our mother's sister's husband is our uncle". Obviously, to translate correctly into Klingon, "uncle" would have to rendered 'IrneHnal and not one of the various other words for "uncle".