" nihongo ga tote mo muzukashii desu yo "
Japanese isn't specific on an object so they don't have words like "a".
It's diffucult/hard, isn't it?
Eigo teesto wa totemo muzukashikatta yo ne?= The English test was diffucult/hard, wasn't it?
Nihongo teest wa muzukashikunakatta ne?= The Japanese test wasn't hard.
Jimu-san to Kanade-chan wa nihongo ga muzukashikunai to omowanai ne?= Jim and Kanade don't think Japanese is hard, right?
There are more forms but when present tense like that it means (something) is diffucult/hard/tough, isn't it?
semoga membantu :)