In many situations in which we act we try to make sure our actions don’t harm others, or are actually beneficial to them. This means that we are taking others into account. We consider how they would be affected by our actions. This is moral consideration.
Moral consideration has to do both with other individuals and with ourselves. In any decision in which we have to choose how to act, we have to weigh different alternative courses of action. How do we, ultimately, decide which one to follow? We may do it according to how it affects just ourselves, or we may do it according to how it affects ourselves and other individuals as well.
However, in those decisions we may not take into account, for instance, how that decision may affect, say, a sheet of paper, a lamp, or a leaf on the ground. Or, rather, we may take into account how it affects these things, not for their sake, but because of the way that affecting them may affect other conscious individuals. This means that we don’t consider these objects morally. The reason for this is simple: they don’t suffer or experience wellbeing, so we can do no harm or good to them.
This means that moral consideration is about which individuals we ultimately take into account in our decisions. Most people have a speciesist perspective and only take other humans into consideration. In fact, many people (such as racist or xenophobic people) don’t even give moral consideration to all humans, but only to some of them. However, because all humans are individuals who, like us, can feel suffering and wellbeing, it is arbitrary not to morally consider them as well.
The same is true of nonhuman animals. They are individuals with feelings and needs and lives that matter to them. They can be benefitted and harmed just as we can. To deny them moral consideration simply because they belong to another species or for some other arbitrary characteristic such as not having a human-like language is speciesism, a form of discrimination.