The phase may measure the difference from zero degrees or relative to another wave.  It may also mean to adjust or synch up that difference.  A digital synthesizer can analyze and manipulated a sound to produce rich and diverse harmonics.

This is how digital synthesizers produce harmonics that revolutionized music in the 1980’s, as in  Enya’s “Orinoco Flow.” Early adopter Delia Derbyshire produced “White Noise, Love without Sound,”  in 1969.  Herbie Handcock’s “Chameleon“, 1973, stretched the limits of Jazz Funk music into a modern era.  Synthesizers became an industry standard used by endless modern artists.

If you feel like you’re out of sync, remember it’s relative and embrace the harmonics.