Please explain what effects does self harm have?

It depends: On the behaviors involved in self harm, and how you are injuring yourself. People do many kinds of things to themselves, and none of it is healthy. Generally cutting and burning of the skin results in some pain and/or bleeding in the short term, and shame in the long-term when self-harming people want their scars removed "as quickly as possible." many such questions have been asked on healthtap.