It's fine in English, although it would normally be a fragment of a larger sentence.
Person A: There's a festival every year in June that sounds good. How about we go next year? Person B: I'd love to but that June is difficult.
Here it would be implicit that June next year is difficult for Person B, not just difficult in general.
It's a proximity issue. Bu is used for something close to you: this. Şu is used for something further away but still nearby: that. O is for something that is a fair distance away: also that, but yonder is more appropriate. Turkish has three demonstratives: bu, şu, and o. When translating into English, there is only two: this and that which makes it difficult to explain the minute differences between them.
I just realized. It is quite similar to Korean.
이-This; 저-That, for something far but still in the vision/can be seen; 그-That, for something that really far or out of sight or something that doesn't exist in the place where they are talking (e.g they talked about a person that in somewhere else).
That's why Korean and Japanese are said to be in the Altaic family. I've also found other similarities that have been told by other person in Duolingo.
Also, I've realized one more similarities. All this three language use verb "to do" to form another verb. They combine the verb "to do" with another verb or noun whereas the "to do" verb is put at the end. Korean is 하다 (hada), Japanese is する(suru). Turkish is "etmek," right?
Well, almost everyone agrees at this point that Korean and Japanese are not related to Turkish :)
Keep in mind that Spanish also has the different "thats." Also forming phrasal verbs with "etmek" probably came to being as a result of influence from Farsi (which does this a looot and which influence Turkish grammar a lot). You see "etmek" being used almost always with Farsi and Arabic loan words :)
The similarities are still interesting though :)
Sorry regardless of the explanations given, this is not used in English. You could say, "That June was difficult" (past tense). You would not use "That" with present tense and the name of a month. You could use "This" with the present and the name of a month. You can use "That" with past and future tenses and the name of a month. Examples: This June is difficult (but this is a bit awkward, it would be better with a qualifier like, for me); That June was difficult; That June will be difficult (or would be difficult...). All of these examples seem like they are responses to a question or an ongoing dialogue.
it is simply how the language is constructed. not everything can be given a concise direct translation. "O noun" is a common thing to see.
it doesn't always make for easy learning, but sometimes we just have to accept that the language is this way. I've been frustrated many times myself
sometimes it's a matter of square pegs for round holes... they both have purpose but don't fit neatly together :)
In my opinion, there is a problem with "tense" in the English translation. Context is also needed, otherwise the sentence is unclear.
In English you would usually say, "That June was" or This June is ...rather than... That June is".
That June was difficult.
Eg. "That June was difficult because sales were very low".
This June is difficult.
Eg. "We'd love to go away for a holiday, but this June is difficult because we have too many relatives visiting"!