there isn'tIn Japanese, ない (nai) means "there isn't" or "I don't have," and adding んだ (n da) to the end shows that you are giving a reason or explaining a situation. While English often uses tone of voice or adds "the thing is..." to make an excuse, Japanese builds this feeling right into the end of the sentence. For example, if you can't go out with friends, you might say お金がないんだ (okane ga nai n da) to mean "(the thing is,) I don't have any money."