That description on the website is a little misleading.
It is not a "lost album", it's just a collection of unreleased Hendrix recordings from '68 and '69 that don't feature The Experience. Jimi was looking to branch out his sound into new territories and he recorded tracks with many different musicians (he practically lived in the recording studio), these are some of those cuts.
The tracklist is below, some titles are of course familiar but these are different versions than anything officially released previously and feature various different backup bands.
Mojo Man. [A Ghetto Fighters tune with overdubs by Jimi]
Hear My Train A-Comin'
Izabella
Earth Blues
Villanova Junction Blues
Somewhere [Stephen Still on bass guitar]
Bleeding Heart
Inside Out
Let Me Love You [with Lonnie Youngblood]
Crash Landing
Easy Blues
Hey Gypsy Boy
P.S. - There are over 600 hours of recorded music in the Hendrix vaults.