"We are not fine."
Translation:हम ठीक नहीं हैं।
These are different conjugations of the same verb, होना. हो is used for तुम (informal "you"), है is used for यह, वह, and तू (this, that, super informal "you" respectively).
BTW you will see people here referring to both यह and वह as meaning he/she/it. This is correct-ish; what to use when is easier to remember if you think of यह as "this" and वह as "that". You can determine how to translate he/she/it/this based on the verb. (It'll also help you remember the difference between यहाँ "here" and वहाँ "there")
There is a difference between...We are not good (people) than...we are not fine/well. आच्छे tends to refer to the character/behavior of a person and is opposite of BAD. Your sentence will be literally taken as ...We are bad ...Therefore, I doubt that you want to say that when you are simply not feeling well.