A character's alignment is an easy way of summing up their moral ideas, and represent their general moral compass. It has 2 axes, and each axis has 5 magnitudes.
Most people tend towards Neutral. On any one axis, 75% of people are Neutral, 20% of people are one step away, and 5% of people are at an extreme. However, adventurers and those that adventurers combat tend to the extremes more so than most.
A benevolent entity is an entity that will go out of their way for the betterment of others, and for the greater good. They are willing to do this to their detriment, if they believe the cost to be worth the benefit, but it's very rare that they would give their life for anything less than the lives of many others; the potential good that could be done outweighs the immediate good.
A benevolent character wouldn't think twice of rescuing people from a burning building, donating much needed supplies, or trying to root out corruption within the city guard.
A moral entity is an entity that will act in the betterment of others if the opportunity presents itself. They are willing to detriment themselves if the cause is great enough, but very, very rarely to the point of risking their lives for strangers.
A moral character would stop a robbery in process, donate a small tithe gladly, or take in a destitute family member.
A neutral entity is an entity which feels no strong need to better themselves or others. This is either due to a commitment to neutrality, or apathy to the cause. This is not to say they don't act selflessly or selfishly from time to time, however.
A neutral character could steal a loaf of bread if they were legitimately in need, or donate a loaf to someone else in need.
An immoral entity is an entity that will act to their own benefit before others. The detriment of others is of little consequence, though particularly reprehensible acts, such as kidnapping, torture, and wanton murder, are still distasteful.
An immoral character would happily engage in petty theft, occasional blackmail, and perhaps a spot of pillaging.
A malevolent entity is an entity that will think of themselves before all else. Their persuit for personal gain often puts them at odds with society, and they'll often think nothing of murder and other such horrible acts, if it serves to further their goals. They may even derive pleasure from the suffering and pain of others.
A malevolent character could engage in grand larceny, treason, or mass murder without moral qualms.
A lawful entity solidly obeys an internally rigorous set of rules. Often, these rules align with the society in which they live. The idea of flaunting or breaking these rules is incredibly distasteful to them, and the idea of others doing so is offensive.
A civil entity largely obeys the rules. They often inherit these rules from the society in which they live, as it's simply easier not to have to put thought into it. They wouldn't be against breaking their rules, if the need was great.
A neutral character commonly feels that rules serve a purpose, but the purpose is largely to keep the masses in line. If something needs to be done that doesn't align with the rules, then that thing needs to be done.
A rebel character has little use for rules. They'll commonly fly off the handle, or act unpredictably, but they won't often go out of their way to cause chaos in the lives of those around them.
A chaotic character revels in the unpredictable, often enjoying watching others panic and struggle in the face of their usurped plans. They'll commonly go out of their way to cause a little mischief and mayhem in the lives of those around them, or persue their goals with little regard for due process.