OK - the glissando is a straightforward white-note gliss, no funny business. The chords are to be sounded as the gliss hand gets to the indicated single note - so taking the first one as an example, the right hand (I'd use right for it though obviously that's up to the player) starts a 2-octave white-note gliss on the D below middle C. As it starts, the LH plays the three black notes, then plays the next chord of three black notes as the right hand gets to the next D, then the third as the RH gets to the top note of the gliss.
In fact it's incorrect as notated: the chords should have quaver (eighth-note) tails on their stems, but anyway that's the gist.