Here[
^] is a list. If I was getting this in interviews a lot, I would both memorise the forms ( actually, I did that any how ), and ask them 'do you mean standard or Boyce-Codd normal form' ? I bet half the people asking you, won't know what that means.
To get to second normal you remove subsets of data that apply to multiple rows of a table and place them in separate tables.
To get to third normal form you remove any columns that are not related to the primary key.
Second normal:
remove the skill id from the second table. Create a joining table so if two students have the same skill, the skill is in table a once, and joined to twice in the joining table.
Your data implies more than one student can have the same email. If this is true, then I guess that would need to be factored out, but they are surely more likely to have the same address or phone number, so it becomes a question of how granular you want to be.
I don't see anything here that directly violates the third normal form, which is one reason that I doubt your interviewers know as much as they want you to think.