A favourite concept.
The organization called Balanced View once described it as "all smells being equal".
Sounds kinda funny, eh?
The meaning of this is that equanimity is like... whether you are smelling lemon meringue pie or cow manure, your reaction is the same. Whether you are "smelling" something pleasant, or something unpleasant, all smells are equal to you. Whether you are having an enjoyable experience or a stinky experience, all experiences begin to equalize, become the same, and we are no longer quantifying everything as good, bad, better than this, worse than that, constantly judging. We neither feel the need to push certain things away because they are viewed as unpleasant, nor try to get close because it is more desirable or pleasant. Our quantification of it is just a perception and perceptions are changeable. Living this way, in a cycle of samsara, we will never get satisfied because we are always running, running, striving, pushing, manipulating. How exhausting it is.
This is the concept of dvesha and raga, our dislikes and our likes, wanting more of the likeable, less of the unlikeable or another way of putting it is having preferences and trying to arrange our reality and our circumstances in such a way that we have more of what we think we want and less of what we think we don't want.
What happens when we no longer have a preference? All states, all circumstances become equal. We are equanimous or undisturbed regardless of whether we are smelling lemon pie or manure. Whether our partner is yelling at us or not is inconsequential to our overall sense of well being and balance. This kind of equanimity under all circumstances takes practice. Practice of being mindful, of watching our reactions, of watching our minds and emotions as the form thoughts and feelings. Meditation is helpful.
These are some pretty advanced practices we are talking about here. The result is that we no longer become so deeply distressed when things aren't going our way, when circumstances aren't exactly to our liking. It means that we can remain peaceful and happy regardless of what chaos and ridiculousness is going on all around us. As a result, we become a powerful resource of stability and groundedness to those around us.
The world is not becoming a less crazy place as time goes by, in case you haven't noticed. To make it less crazy, cultivate the stability within so as not to be contributing your own chaos to that of the world around you. Being a stabilizing grounded force doesn't mean that we are unfeeling or cold like statues, it just means that we don't react in a knee jerk fashion to outer stimulus.
There is a moment or two between when we recognize and become aware of our thoughts, feelings and emotions as they arise around a situation, and when we mindfully select how we are going to choose to respond, if we choose to respond at all.