This new database is an index to all births in New York City from circa 1880-1912 (or ca 1917 in some cases outside of Manhattan). But unlike a typical birth index arranged by surname or by date, this one is arranged by the child's place of birth, the actual exact street address!
There are approximately 2.8 million names in here, maybe more. Remember that this is an index. Armed with this data on the index card with your ancestor's name, you can then order a copy of the actual birth certificate from the city.
Want to skip right to the records? See New York City Geographical Birth Index on Archive.Org