What is the European Commission?

The European Commission is the part of the EU machinery that proposes legislation for the Parliament and Council to vote on, implements policies and manages budgets once they are adopted, and represents the EU internationally (in areas other than foreign policy and security policy). Jointly with the Court of Justice, the Commission is responsible for enforcing European law.

The Commission proposes legislation at EU level only when that appears to be the most effective way of addressing an issue, and it takes expert advice when drawing up proposals. The principle of subsidiarity means that action is always taken at the lowest possible level, so if a national or regional approach can work, then an EU-level solution is not proposed.

Source:

The European Union explained: How the EU works, European Commission, 2014