This is how I structured mine: your role generally, your role specifically (what did you do in-depth), transferable skills you have learnt and the outcome of your role. (How did it affect your team members etc)
Example:
I interned with a production house and participated in the production of a historical documentary. I conducted significant historical research and collected archives for the documentary. Furthermore, I organised the documentary's footages and produced transcripts. I developed project management skills such as organising my workload and time management. I also gained an insight into the production of a documentary. with my contribution and the collaboration between my team, the documentary was successfully released on the deadline we arranged for and it was aired nationwide.