Self-care is when you take care of yourself, not just physically but emotionally too. You're able to meet your emotional needs, you don't depend on someone else to meet them. For example, when you're engaging in your hobbies or whatever it is that you love doing, that is a form of self-care because you are doing something you love because it brings you joy. When you are trying to improve yourself as a person by exercising, or reading books to broaden your mind, you are taking care of yourself since you are trying to be the best version of yourself that you can be.

Basically, just like a loving parent treat their child with love and care, and tries to make sure that their child succeeds in life by encouraging them to be the best versions of themselves, you treat yourself like how a loving parent does.

Self-care is a very important step in building up self-esteem. When your self-esteem is healthy, you are able to see which person is good for you, and you are able to recognize toxic people with ease.