The book “Zakat Al-Fitr” is discussing the significance, purpose, and benefits of Zakat al-Fitr.
Zakaat al-Fitr is a kind of charity (sadaqah) that is obligatory at the time of breaking the fast of Ramadan. The word zakaat is connected by idaafah (genitive structure in Arabic grammar) to fitr because the occasion of breaking the fast is the reason why this zakaat becomes obligatory.