Hello Omar,
In general, using Google Cloud Platform, you may try hosting your application in two different ways. The first is by using Google App Engine where the idea is to focus on your code and build your application without worrying about the underlying infrastructure. However the infrastructure that is hosting your app is regional, and you have to choose the region before deployment (project creation). For example, if you choose to have your application in europe-west2 (London), then your customers in London will have faster response time than other customers from other parts of the world.
The second approach is to manage your own virtual infrastructure through Google Compute Engine. For example, you can create as many VM instances as you wish in multiple regions, and run your application accordingly, load balance and autoscale the VMs, use Cloud CDN, etc.