The denom is the unit of the amount of the balance. In Cosmos SDK, the unit is in micro (u), hence it is uvoi. A micro IOV is 0.000001 IOV, or 1e-6 IOV.
Receiving and sending IOV Tokens
Once your address is set up, you can receive IOV tokens (and starnames) to your address. You can also send IOV tokens and starnames you own to other star addresses. The command for IOV Tokens is simply send