An International Company is one which has a trading presence in more than one country.
This means that the company must an office in more than one country. They must be able to provide evidence of this such as providing their registration certificate or licence number in that country or a VAT/TAX letter displaying the address of the office in that country.
The UKVI will verify this, both online and through access to internal resources, that this evidence is genuine.
If the company who wishes to sponsor you meets this requirement then they should provide you with a letter which details the terms of that sponsorship.
If you are being sponsored by a company which does not meet these requirements then you do not meet the financial requirements as defined in Tier 4 guidance. The company would have to transfer all the required funds for both course and living costs to your personal bank account where you would then be considered a ‘self-financing student’