Shawwal is the tenth month of the Islamic lunar calendar. It comes immediately after Ramadan. Shawwal is also the first month of the Ashhur al -hajj – (the months of Hajj). Eidul Fitr also occurs in this month. Regarding the six fasts of Shawwal Abu Ayyub (ra) reports: The Messenger of Allah (PBUH) said,

“He who observes As-Saum (the fasts) in the month of Ramadan, and also observes As-Saum for six days in the month of Shawwal, it is as if he has observed As-Saum for the whole year.”
[Muslim].