The Y-chromosome (paternal) haplogroup provided in the Paternal Line feature is one small part of your ancestry analysis. The 23andMe® Personal Genome Service provides you with information from all branches of your family tree using your autosomal DNA in features like Ancestry Composition.
Only males will receive a Y-chromosome (paternal) haplogroup assignment. Because females do not have Y chromosomes, females do not have paternal haplogroups. However, a woman can learn about the origins of some of her paternal ancestors from the paternal haplogroup of her male-line relatives, such as her father, brothers, and paternal uncles. Women can also link the paternal haplogroup of her male-line relative to her profile.
In order to link a haplogroup in the Paternal Line feature for your profile, first make sure that you are sharing genomes or are in the same account with someone on your direct male-line. When you next go to your Paternal Line page you will see the option to set any sharing connection's paternal haplogroup as your own.