Conversation so far:
what is the significance of mass moment of inertia
Rotational inertia is used to calculate angular momentum and allows us to explain (via conservation of angular momentum) how rotational motion changes when the distribution of mass changes.
what is the symbol for mass moment of inertia
The common symbol for Moment of inertia is I.

Question: how about si unit
Self-contained rewrite: what is the si unit for mass moment of inertia