protoc is the compiler for .proto files. It generates language bindings for the messages and/or RPC services from .proto files.
Because protoc is a native executable, we build and publish a protoc executable (a.k.a. artifact) to Maven repositories. The artifact can be used by build automation tools so that users would not need to compile and install protoc for their systems.
The pom.xml file specifies configuration details used by Maven to publish the protoc binaries. This is only used internally for releases.
The published protoc artifacts are available on Maven here:
https://repo.maven.apache.org/maven2/com/google/protobuf/protoc/
The version of the protoc artifact must be the same as the version of the Protobuf project.
The name of a published protoc artifact is in the following format: protoc-<version>-<os>-<arch>.exe, e.g., protoc-3.6.1-linux-x86_64.exe.
Note that artifacts for linux/macos also have the .exe suffix but they are not windows binaries.