According to the Ancestry information blurb:
"This database includes all 32 volumes of Alexander Chalmers’s General Biographical Dictionary, which, according to its subtitle, contains “an Historical and Critical Account of the Lives and Writings of the Most Eminent Persons in Every Nation; Particularly the British and the Irish. From the Earliest Accounts to the Present Time.” Entries are alphabetical by name. Ancestry World Archives Project volunteers have indexed all 32 volumes by name, birth dates, and death dates to improve database usability."The original was published about 200 years ago so don't look for anyone more recent.
If you don't have access to Ancestry digitized editions are available free on Google Books and the Internet Archive.