The term 'Female Swans' refers to female swans, which are members of the Anatidae family of birds. They are typically larger than their male counterparts and have a distinctive curved neck. Female swans are known for their grace and beauty, and they often mate for life. The term 'PENS' is a four-letter word that can refer to a type of enclosure used to keep animals, such as swans, confined. It can also refer to a writing instrument used to create written words.