Answer
The name of $Ba_3N_2$ is : "Barium nitride"
Work Step by Step
1. Identify the positive ion, and name it.
$Ba^{2+}$ is the positive ion.
So, the first name of the compound will be: "Barium";
2. Identify the negative ion, and name it.
$N^{3-}$ is the negative ion.
This is a monoatomic anion, so it will receive the element's stem name: "nitr", plus the suffix "ide": "nitride"
3. Putting those two names together:
Barium nitride.
