The price of Cloud Functions consists of multiple factors. These include the number of Invocations, Compute time, and network rate (Networking). These are shown in the following diagram:
Remember that there is a monthly free usage tier you can play around with without generating any cost. At the time of writing this book, it consists of 2 million invocations, 1 million seconds of compute time, and 5 GB of egress network traffic. Enjoy it!