What is meant by mounting?

Does Mounting a file is equivalent to creating a file ?

No, it doesn’t equivalent.

The mount command attaches the filesystem of an external device to the filesystem of a system.

It instructs the operating system that filesystem is ready to use and associate it with a particular point in the system’s hierarchy. Mounting will make files, directories and devices available to the users.

It mounts the external storage devices like hard disks, pen drives, USBs etc.