When people say, "You are a smart-ass!", they are using a colloquial and somewhat informal expression to describe someone who frequently makes sarcastic or witty remarks that may come across as clever or intelligent but often with a hint of arrogance or an intention to be condescending.
Being called a "smart-ass" is generally not considered a compliment, as it implies that the person is being overly sassy, disrespectful, or showing off their intelligence in an annoying or disrespectful way. It's a way of telling someone that their comments or behavior are seen as irritating or inappropriate, even if they may be clever or intelligent.
As with any expression, the interpretation may vary depending on the context and the relationship between the people involved. Some people may use it playfully among friends, while in other situations, it could be considered offensive or rude. It's important to be mindful of how our words may be perceived by others and to communicate with respect and sensitivity.