Hi! Is there an error in this example?
彼は暇なときに本を読みます。
He reads books when he is bored. (Hobby)
暇 translates as free or am I mistaken?
PS I didn’t find any report buttons for grammar points. Is it appropriate to post this kind of questions here or should I use support for this?
暇 is one of those words we tend to misunderstand due to its literal translation and cultural context.
I think that it has a pejorative nuance for Japanese people, free time because you cannot think of something useful to do, among other uses. There is this somewhat sarcastic expression, “暇だね” which could be translated as “Get a life!” (“You have nothing to do, don’t you!?”).
暇 is basically spare time. Like what you do when you are free. So the sentence is literally “He, in his free time, reads books.” Na is modifying とき. What type of time are they talking about? The time that there is spare time.
Adding to what the others have said, 暇 is one of those words that has a different meaning based on context (as is frequently the case with Japanese). Just remember that it can also have the “bored” meaning as well.
at the bottom of every grammar point you should see a lil’ area that looks like this
first button links to the corresponding forum thread about the GP (usually some good discussion and answered questions there) and the last button is for reporting any bugs or errors~ 
Thank you for the replies! I checked jishou before asking this question but there was nothing about “bored” nuance. A before that I saw 暇 used only when describing actual free time. Like “are you free?” “Do you have free time?”
One thing that Bunpro does, often to my annoyance, is that the English sentences they provide are “localizations”, they aren’t literal translations. It’s not so much of a nuance I would say it’s more of a creative way of translating the sentence.
If anything I would say that this particular case would be an omission on Jisho’s part. 暇 most certainly has the nuance of ‘bored’ in many sentences.
No translation dictionary is perfect unfortunately. If you google 暇だ or 暇だな and select images, there are lots of examples of the ‘bored’ nuance.
おはようございます
それに, I was just watching Kaname Naito’s video on ‘talking about time’. Please go to 13:20 to hear what he says about ‘暇’. As usual, the whole video is quite interesting, so it is worth to take the time to see it in full.
良い一日を
If there is a subtle nuance in some of these sentences, I feel like it would be helpful to have a footnote to indicate learners, “Hey, this translation we’re doing, there’s a reason why we said it this way and not what a dictionary had.”
This does bring up an issue I have noticed when testing the new reading review mode which is sometimes a less “obvious” English translation is used. I think less “obvious” translations would make the reading mode a bit tricky for the lower levels as newer learners might get tripped up. As an intermediate learner I feel comfortable saying whether my translation was close enough or not but a beginner probably isn’t in a position to do that. This is only a problem if a user is using the reading review mode though.
(edited to remove an unnecessary discussion of 暇 as basically beating a dead horse at this point)