In the Parable of the Good Samaritan, Jesus explained not only who our neighbor is, but also what love of neighbor looks like. He also taught the importance of the corporal works of mercy (feeding the hungry, visiting the imprisoned, etc.) when He spoke of the King separating the sheep from the goats (Mt 25:31-46). I think our society gets this. Even if many individuals don't actually practice it as often as they should, we as a society recognize and value serving the poor, helping those in need, etc.
In our day, an aspect of loving our neighbor that is frequently overlooked, on the other hand, is how we speak of one another. People realize that it can be a bad idea to say negative things straight to someone's face, but they seem to have few qualms about saying almost anything behind someone's back.
In Taming the Tongue, Mark Kinzer provides a very sobering examination of how seriously God takes this subject. For example, he writes: "I know of few verses in all of Scripture more spine-chilling than [Mt 12:36-37]: 'On the day of judgment men will render account for every careless word they utter, for by your words you will be justified, and by your words you will be condemned.' "
Why does He care so much about what we say?
It is due to the power of the word.
Obviously, insulting someone directly is unkind. But bad-mouthing someone behind their back is also hurtful. For one thing, our words could find their way back to the one about whom we speak. Our listener might report our words, or the subject of our conversation might overhear us, or someone else might overhear and report our words.
But even if that person never learns of what we said, our words have still hurt them, for we have hurt their reputation. Almost everything we say about someone has the potential to build up or tear down that person. This is why it's so important not only to avoid slandering someone (speaking a negative truth), but also to guard against uttering careless words about them.
St. Philip Neri, who is known for his dedicated service as a confessor, once helped a habitual gossip realize the seriousness of her vice. For her penance, he had her take a feather pillow to the top of a tower on a windy day, cut it open, and shake the feathers out. Then she was to go down and recover every feather she'd released. She naturally retorted that that would be impossible. He responded that it would be easier than to retrieve every harmful word she'd spoken or repair its damage.
Hence, what we say or refrain from saying is a key aspect of loving our neighbor.