Your skills consist of all the things that you have focused on during the study years and on which you have accumulated experience.
Write here all the things you know well, things you have theoretical knowledge of through studies, projects, things you have gained in-depth experience of or familiarity with through internships / work, or knowledge and skills you have gained in voluntary work in organisations and through hobbies or sports. Employability skills are general skills that are necessary for success in the labor market at all employment levels and in all sectors.
You can do a sort of a mind map. Below you'll find an example of a learning map.
You can do a skills map by paper and scan the chart or you can do it using e.g. MindJet.
Completing a skills map takes usually 20-40 minutes, but it is useful to return to this after some time, since you probably will remember new situations when you learned something important.