In cartomancy with playing cards, Queens are generally representative of women, and this is just about their only role. It is very rare that they come up to signify something else. That being said, they also have a connection with receptivity, nourishment and growth.
In some systems, the significators for the querents vary, but in the one I have been taught, it’s normally the Queen and King of Clubs that represent the querent.

The Queen of Hearts is usually a woman who is known to the querent. She represents a mother, daughter, relative or close friend. In general, she is a woman who has the querent’s best interest at heart, or at least should (you’ll need to check the surrounding cards). Even if she is not related, she could stand for a positive woman in general. For a lesbian querent, the Queen or Hearts can be the partner. The Queen of Hearts is also a symbol of acceptance and receptivity. It shows an environment where the querent thrives and is allowed to grow. Broadly, it confirms the receipt of something and it is a symbol of motherhood.

The Queen of Clubs is the female querent. If the querent is a man, she is usually the partner, either actual or perspective. If this interpretation is out of the question, she is still a woman in the querent’s life, usually not related to him. The Queen of Clubs is also connected to the idea of tending to something, working on it to make it grow or perfect it. She is not a symbol of great accomplishments, but she signifies honest effort, and doing what’s honorable. She is connected to harvest.

The Queen of Diamonds is a woman outside of the querent’s immediate circle. She is an acquaintance, a superior, a businesswoman, a professor. Her role is ambiguous, because her primary loyalty is to herself and her interests, but this doesn’t make her evil (after all, the woman you buy flowers from sells flowers to make money, not to please you). Compared to the Queen of Hearts she can be colder. She can also be a rival. The card is also a symbol of prosperity and of reaping the good fruits of one’s labor.

The Queen of Spades is a lonely or elderly woman. She can be an enemy or a difficult person. She doesn’t love the querent, nor does she further the querent’s aims (this is a great difference with the Queen of Diamonds, that the latter’s aims can allign with the querent’s, while those of the Queen of Spades are usually opposite). She can also be a woman who is very powerful, wears a uniform or represents the law. She can be an ex or a doctor. The card is a symbol of things that rot or are overripe or spoiled, and also signifies lack of acceptance (including lack of submission) privation, hunger, miscarriage. Finally, the card signifies falsehood, false words, false promises and false people.