Okay kiddo, let me try to explain it to you in a way that you can easily understand.
Do you know what a Brahmin is? They are a group of people in India who are considered to be very wise and knowledgeable. They are usually priests or teachers and are respected by everyone.
Now, a pushpaka means 'made of flowers or plants' and is actually a kind of flying chariot in Hindu mythology. It is said that the pushpaka brahmin was a very wise Brahmin who had the power to control and fly this magical flying chariot, which could take him anywhere he wanted to go.
So basically, the pushpaka brahmin was a wise person who could fly anywhere in his magical flower chariot! Cool, right?