You will get 5000 free bandwidths for normal trading every day (you can also get more bandwidth resources by freezing TRX). After bandwidth is exhausted, each transaction will deduct a small amount of TRX for bandwidth deduction. This part of TRX is charged by main chain.
During the trading, calling contract will result in energy consumption. When token contract is called, if TRC20 token contract freezes the energy for users, users do not need to consume energy; if there is no frozen energy, users need to freeze certain TRX to get energy. When energy is insufficient, you can trade normally, but the main chain will deduct a small amount of TRX for resource deduction. This part of TRX is charged by main chain.