Hello Aymane, App Engine is indeed perfectly suitable for a small business website. This being said, there are many factors to consider before choosing which product to host your website with.
App Engine aims to make creating and running your website as easy as possible. If has a free tier and the ability to scale down to zero active instances in situations where your website isn't getting traffic, lowering your costs, as well as the ability to scale the number of instances serving your website up to allow you to handle any amount of traffic. One thing that is important for you to keep in mind is that App Engine offers a number of services that are not available on other products, which might require you to refactor parts of your application if you wish to eventually move to another product.
Other compute options are also available such as Google Compute Engine and Google Kubernetes Engine. To help you decide which one is best suited to your needs, check out the this
comparison of the main compute products on the Google Cloud Platform.
I hope this helps, let me know if you have any other such questions or need more detail.