Neutral is an alignment with multiple meanings, not all of which may apply to an individual, it is most commonly associated with those who do not have any particular moral inclinations.
Neutral characters cannot be represented by one specific outlook, there are several reasons a person may be considered neutral. Neutral is the default for those who have not taken a moral or ethical stance in any direction either good or evil nor lawful or chaotic. This also includes non-sentient animals that have no capacity to choose and primarily follow their primitive, moral-less instincts. Those who have chosen to enforce a 'natural balance' between all the other ethics are also considered neutral, these often include those who worship the perfect balance of nature, particularly druids. Those who have the 'natural balance' enforced upon them may feel differently about the neutrality of such people often deriding them as evil. Neutral is also the alignment for those who seek a centered existence, with moderation in all things, Ascetics who take no side and instead seek spiritual perfection of the self are an excellent example of this.
One of the best examples of a neutral deity is Gozreh, a deity who balances natures nurturing side with its more destructive forces. If Gozreh embodied just one of these aspects he would probably be a different alignment but because he represents the two in perfect balance he is considered neutral.