

It entails exactly what you see in the world. Humans trying to come up with some universal good and evil and then fighting each other because they believe their definition is better.
“Morality” in itself is a human concept, like every word in general.
This realization often entails a kind of nihilism too, unfortunately, as a sort of rebellious backlash against any ideas of harmony with others.
Vast majority of people don’t want to directly cause suffering to others. Then there’s a lot of opinions on how much you “should” (a thinly veiled callback to universal good and evil again) endeavour to reduce the indirect suffering you cause, and also how to define suffering.
Ultimately it’s always just people’s personal values clashing and best you can do is figure out what your values are, and find people who share them. You can’t really force people to value anything they don’t - you can only teach it if they are willing to learn. Or you can force compliant behavior despite their differing values - if your value system allows forcing. If your values allow for forcing compliant behavior on others, then you must of course accept that others will try to use force as well. If you don’t allow forcing, then you pretty much need to be prepared to die for the ability to live according to your values.

Practice. I’ve learned it by meditation (specifically paying attention to the whole of your experience), and so have many other people I know.