A primary source is a document that was created during a particular time period. This may include first-hand accounts of historical events and time periods, such as speeches, diaries, letters, and news coverage. Creative works such as fiction, poetry, and art are also considered primary sources.
A secondary source is about a primary source. It analyzes, interprets, and comments on the rimary source. Books and scholarly journal articles are secondary sources.
For example:
A speech by Harvey Milk is a primary source.
A book about Harvey Milk or his speeches is a secondary source.