Binance, and some other exchanges, operate on a maker-taker fee structure, providing different trading fees to makers and takers.
Maker fees on Binance are generally lower than taker fees. That’s because a “maker” provides liquidity for the order book (by placing an order that may be matched in the future, this “makes” the marketplace; like products on a store shelf) whereas, a “taker” consumes the book liquidity by ‘taking’ an order from the order book (taking away inventory from the store).
You become a “maker” when you place an order and it does not trade immediately, so your order stays in the order book and waits for someone else to fill/match with it later.
The "taker" is someone who decides to place an order that is instantly matched with an existing order on the order book.
(*Trades from Market orders are always Takers, as Market orders can never go on the order book.)
Trading fees on Binance are paid once the trade executes. The moment your order fills/trades, it is defined as either the “maker” or the “taker” of that trade. You will then pay either the maker or taker fees depending on whether or not you were the maker, the order on the book, or the taker, the incoming order.