A computing platform includes some sort of hardware architecture and a software framework (including application frameworks). The combination allows software (app's) to run. Typical platforms include a computer's architecture, operating system, programming languages and related user interface.

A platform is a crucial element in software (app's) development. A platform might be simply defined as a place to launch software. The platform provider offers the software (app's) developer an undertaking that logic code will run consistently as long as the platform is running on top of other platforms.
It actually means execution of the program is not restricted by the type of operating system provided. It has mostly replaced the machine-independent languages.