In theory, it does that by making it painful to horde cash.
In a deflationary environment, holding cash is rewarding. Cash grows in real terms, risk free, at the rate of deflation. Meanwhile, risky business investment becomes even harder to justify in a declining price environment . . . why buy inventory, or build a factory, when it's value constantly depreciates? Similarly, why hire a worker at a downwardly inflexible wage to produce widgets whose price continually declines?
That process gets upended when people expect or experience inflation. Hording cash becomes painful, while consumption is rewarded and risky investment becomes a better alternative to the negative real rates earned on cash.
I may be giving us too much credit, but "not sure" seems like the most reasonable answer when questioning how something that has rarely been tried before will work.