Hi Kaushik:
GSoC has 3 evaluations, so you will make a plan with 3 phases / milestones (probably incremental).
You would need to give some detail, for example which topic/issues you will include in each phase.
For each phase, a deliverable should be produced, so it could be evaluated with some acceptance criteria.
You can explain what you will be included in each of the 3 PRs: minimum / full goals, any resulting documentation, build instructions / setup and online "website".
Applications are still not open, so there are no template proposal to follow yet.
You could take a look at my proposal (when I was student), just as an example:
Best Regards
Mariano Reingart