I have read the Prajnaparamita Heart Sutra twice but I don’t understand it. What should I do?

You don’t need to understand. Those are the scriptures of Buddhas and Bodhisattvas. If you don't understand them, if you understand them, you will be a Bodhisattva, just like ants cannot understand human language. As long as you read it carefully, the Heart Sutra is used to help open up our wisdom. Before reciting it, say: I pray to the Great Merciful and Great Compassionate Guanyin Bodhisattva to protect me and increase my wisdom and energy. How many times have I recited the Heart Sutra? If you recite it, you will become more and more wise and enlightened.