"Post pill" often refers to the period following the discontinuation of hormonal contraceptives, most commonly birth control pills. During this time, individuals may experience a variety of changes in their menstrual cycles and overall hormonal balance as their bodies adjust to the absence of synthetic hormones.
Use typically refers to the purpose of taking birth control pills, which is primarily to prevent pregnancy. However, hormonal contraceptives can also be prescribed for other medical reasons, including managing menstrual cycle irregularities, reducing menstrual cramps, treating acne, and helping alleviate symptoms of certain hormonal disorders.
If you have specific questions regarding the "post pill" phase or use of hormonal contraceptives, feel free to ask!