the data transfer into and out of the B1S VM is not included in this free usage and is subject to additional charges.
Azure calculates data transfer costs based on the amount of data that is transferred in and out of Azure services. The cost of data transfer varies depending on the region where the data is transferred and the type of data being transferred.
For more information on data transfer pricing, you can consult the Azure pricing page and filter for "Data Transfer" to get the up-to-date information. It's important to keep track of your data transfer usage and costs, and plan accordingly to ensure that you stay within your budget.