An order book, simply put, is a list of people who are buying and selling a particular coin/token. The order book is split into two halves buyers and sellers. Each entry in the buys order book will show the price that people want to buy at and how much they are prepared to buy. Inversely, sellers will list what price they want to sell at and how much to sell. When a seller and a buyer both agree on a price, a trade happens and the coins/tokens change ownership.
Swyftx does not provide an order book of its own. Instead, it sources order book liquidity (buyers & sellers) from multiple global exchanges, including Binance, to deliver you the best possible prices and spreads.