I have never come across such a term and anybody asks in applications. Usually h-index is counted for the impact of one's publications. This value can be found in your Scopus ID and Google scholar profile. There is another term-self citation which also can be found from your Scopus ID.
Self Impact Factor ......... it might be impact factor as 1st author ... this term is never used... I agree with Isaac Dinaharan ... another term mistaken might be self-citations,... in which one refers his own relevant papers in paper as author ...???
Usually, h-index or similar metrics provided by famous platforms like Google Scholar can be very useful. I have never come up with the term self impact factor.