Translation:It's fun to sing at Karaoke.
It's rare for kanji to be rejected, and you can usually just submit an error report and it will be added. If it was a "type what you hear" question, though, there's a bug with the duolingo programming that only allows one specific combination of kana and kanji to be accepted as correct, which you can read more about in the comments in this thread on the forum.
I put "it is fun singing at karaoke." Duo rejected "singing" in favor of "to sing." But doesn't the "TIP" on this very lesson say that adding "no" has the effect of causing it to "become either “to swim” or “swimming”."???
This one "わたしは本を読むのがきらいです。" looks the same to me, but it rejects "to read" in favor of "reading." Is it arbitrary and Duo is just being mean? Or am I missing something (ALWAYS a possibility)?