Complex sentence: Black History Month is an annual observance for remembrance of important people and events in the history of the African diaspora celebrated annually in the United States and Canada in February and the United Kingdom in the month of October.
Split into simpler sentences: Black History Month is a national annual observance for remembrance of important people and events in the history of the African diaspora. It is celebrated annually in the United States and Canada in February and the United Kingdom in the month of October.