This is just one perspective, but people-pleasing is when you go overboard with being considerate of others – to the point that you lose yourself. So like the one friend who will say they like all the same things as you, say yes to everything, never disagree, etc. just because they desperately need you to like them. They don’t have boundaries, so even when someone hurts them, they’re like “it’s okay, I don’t mind!” They’re missing a bit of self-respect.
There’s nothing wrong with being kind or considerate of others! It’s really important to have to form deeper relationships. The problem is when seeming ‘nice’ takes the place of your personality or being honest about your real self, because you value other’s validation more. People can sense that and it can put them off because they want to get to know the real person. People-pleasers can play the character that they think others want them to be, instead of putting in the work to like and value themselves and communicate their own needs and boundaries.