Is your profile already complete? So, it's time to fill out the self-assessment.
A list of the skills chosen by the company will be presented, such as names of languages, frameworks and other structures. Then, just move the cursor to define the level at which you are in relation to the knowledge/mastery of the mentioned technology.
In JavaScript, for example, do you have None, Basic, Practical, or Advanced knowledge? Mark the most coherent answer.
You will have 10 minutes to complete the self-assessment. But, generally, it is completed before this deadline.
With a complete self-assessment, the company better understands individual and team gaps, thus being able to promote improvements.