Describe the project being very specific, you can use the Twitter standard: no more than 280 characters: complement the information: the skills learned or reinforced in its realization and how you faced it, prove to be proactive in the search for solutions.
Demonstrate in this description the skills of a programmer: such as having commitment, having perseverance and accepting alternative solutions. Remember that being a portfolio you are not selling the project, you are selling yourself, it reflects the resources used: Frameworks, libraries, platforms, etc.
If the project was collaborative, reflect it in this description, that will demonstrate communication and/or leadership skills. Additionally, if you made use of the mastery of a second language, it will reflect on you professionalism.