A Friendly Neighbor can target a player at Night to tell them that they are Town. The target will receive a message saying that the Friendly Neighbor is Town. This role does nothing else - the Friendly Neighbor does not know the alignment of the person who got the message.
Friendly Neighbor bears no association with the Neighbor role.
Friendly Neighbor is necessarily Town-aligned.
Town-aligned Friendly Neighbor is considered Normal on mafiascum.net. Messages sent on behalf of a Friendly Neighbor must be identical.
Use and Power
Friendly Neighbor is stronger than Innocent Child. Innocent Child's mod-confirmed innocence is revealed to everyone at the same time, making them a prime kill target for scum. Friendly Neighbor can limit this revelation to people they trust, allowing them to stay in the game longer.
Beyond that, they are as strong as a single confirmed innocent.
Friendly Neighbor is nearly impossible to frame as a liar. If you are scum and receive a Friendly Neighbor greeting, you probably are not served by lying and saying you didn't get it.