Imagine a purchasing manager in a manufacturing company.
He does not just ask for prices. He has to find suppliers, compare terms, monitor deliveries, renegotiate when conditions change, and handle when a link does not fulfill its commitments. That position exists partly because continuously using the market for these tasks is still costly.
Ronald Coase views the enterprise from just that angle. His point is not that the market is useless. His point is that using pricing mechanisms is not free. The very act of finding prices, negotiating, forming contracts, monitoring, and resolving disputes is a type of cost. When those costs are high enough, some tasks performed within the business are cheaper than doing them through the market. This is a very important part of how he explains why businesses exist.