This refers to an effort to not take any set position on an issue or not taking a side in a conflict or disagreement - this, in a way that opens up space for others to not be unduly influenced in making their own judgments and decisions.  

While some use this term to imply an absence of bias or prejudice, others argue that being completely free of a particular standpoint is a philosophical impossibility.  Rather than being free from having a perspective, some believe acknowledging and articulating those biases allows a more fair and "neutral" atmosphere to emerge.

Often neutrals say – I’m impartial on the issue but an advocate for the process of [dialogue, mediation, negotiation etc]

Whereas neutrality used to be seen in a negative light ("The darkest places in hell are reserved for those who maintain their neutrality in times of moral crisis" -Dante), the term has taken on largely positive connotations of fairness and balance in the modern era.