Question

is an opinion from another person
involves both positive and negative comments
comes in a friendly manner
is meant to improve the outcome

1. this is

communication
interpersonal skills
someone picking on you
constructive criticism

Explanation:

The described characteristics—external opinion, balanced positive/negative comments, friendly tone, and improvement focus—match the definition of constructive criticism. Communication is too broad, interpersonal skills are a set of abilities (not the feedback itself), and "someone picking on you" is unhelpful and not friendly.

Answer:

constructive criticism