While up to a specific number of calls are considered free for using the Google Maps API, there are a few caveats to this count. According to past information, the number of free calls per day was set at 25,000, but this information is subject to change, so it is always advisable to refer to the official pricing page.
Furthermore, here is an explanation of how the API call count works. It is characteristic that just loading the script is not counted, but is counted when the map is actually displayed. This is a mechanism to prevent users from being charged if they preload the API but do not actually use it.
It should also be noted that the act of placing a marker on the map itself is not counted as an API call. However, additional fees may be incurred for certain functions or requests, so please check the official documentation for details.
In general, the fee structure and counting mechanism of Google Maps API is on the complex side. When considering the use of this service for your project, it is important to fully check the official information beforehand and understand the expected costs.