If someone is supportive, they help you and make you feel better.
Being supportive is a very good thing. It means someone cares about you and wants to help you.
Examples:
My mom is very supportive when I feel sad.
The teacher was supportive when I made a mistake.
She is always supportive of her friends.
The dog was very supportive when I was sick.
The superhero was so supportive that he helped everyone in the city.
The supportive hug made me feel better.