A public cloud is the cloud as most people know about: a public cloud that everyone can access. Your data, applications and tools are then stored on a shared, online infrastructure that is shared by multiple users. Your data is only visible to you, but other organizations also use the same infrastructure. Good examples are services such as Azure, Google Cloud or AWS. You usually pay a fixed cost per month and per user for access to a public cloud application.
From experience, we know that some IT processes and apps thrive better in a public cloud environment. For quickly scalable applications, the public cloud seems a suitable cloud solution. Other data or workloads still run best on your private servers in a data center.