shrinkage limit is the maximum water content at which if we reduce water content further than soil volume doesn’t change,
we can also say that at shrinkage limit, water is in just saturated stage.
let’s see the graph of water content and volume change with shrinkage limit

ws= shrinkage limit
wp= plastic limit
wl=liquid limit
at below shrinkage water content water is spill out/remove from voids of soil and that voids fill with the air. Hence voids doesn’t change, so volume doesn’t change. and soil become 3 phase structure air, water and solid particles.