this means to do sexual things with a girl/boy who hasnt done anything yet. not neccesarily sex, but like fingering her for the first time, or giving him a handjob.
if im with a girl who has not done anything sexual at all and i make out and finger her..then i just trailblazed her/ am "trailblazing" her.
While our lifespan is the number of years we will live, our healthspan is the number of healthy years we will have and our sexspan is is the number of years we will continue to be healthy enough to continue having an active sex life.