Whenever you're talking about more than one thing, you should always use "are" instead of "is". Also when you're describing a noun in a sentence you need to say which one you're talking about. If it's obvious which flowers you're talking about, you can just say "the flowers". You can say this if you're talking about the only flowers in the room, if someone's given you some flowers and you're commenting on them, or if someone has already mentioned the flowers and they know you're talking about them. If you say "Flowers are giving off an exquisite fragrance" without starting with 'The' it sounds like you're talking about all the flowers in the world. Which could well be true! But if you're talking about specific flowers then you'll want to start with 'The'. If it isn't obvious which flowers you're talking about you should instead say "These flowers", or "Those flowers," "Her flowers," or anything similar, depending on which flowers you mean. :) And 'fragrance' is one of the nouns where you need to say how many of them there are in the sentence as well. Since flowers can only have one fragrance, you'd say "a fragrance", or in this case "an exquisite fragrance". If you're talking about just one flower: "The flower is giving off an exquisite fragrance." If you're talking about more than one flower: "The flowers are giving off an exquisite fragrance." If you're talking about both a flower and something else: "The flower and the perfume are giving off an exquisite fragrance." And as you probably already know you also use "are" when talking about 'you'. This is the only other time you'd use it. "You are learning English." Hope this helps!

The flowers are giving off and exquisite fragrance. The aroma of the flowers are intoxicating. The smell of the flowers are truly exquisite. The flower's fragrance is truly amazing. Just some examples.

"The flowers are giving off an exquisite fragrance." In U.S. English as of 2016 this is slightly formal or literary language. In many contexts it would be more appropriate to say simply "The flowers smell good," or "The flowers smell wonderful." It is usually good style to use the plainest words possible. You should only use fancier words if they actually express your meaning more precisely, or if the cultural context calls for them. Is there an important difference in meaning between "The flowers smell wonderful" and "The flowers are giving off an exquisite fragrance?" There might be, if the idea is to focus attention on what the flowers are doing instead of what the passerby is experiencing. "The flowers are giving off an exquisite fragrance, but he is not aware of it because he has a cold."