We can lie. We can deceive. We can tell people, you're looking so great today and not mean any of it. But we can do that because we have words and we can lie about that. We are all actors.
If everyone went around saying exactly what they felt about the other person, no one would ever get along.
You're always telling the boss the things that they want to hear. You always reply "I'm okay" when someone asks you how you're doing even if you're not doing so great. You're an actor.
In another instance, you're never the same with two different people. The way you are in front of your father is not the same as you are in front of your son or in front of a colleague. You're completely different person. Your jokes are different. Your body language is different. You're an actor.
Some people are good at it. Some people are not, but we are all actors.