1,
PS is the abbreviation of postscript (remark, which can also be interpreted as postscript and postscript)
1, (signature at the end of the letter) Furthermore, there is; P.S., P.S. , PS or p.s.
2. Appendices (to books, etc.). ); postscript
3.[ English] Conclusion (after news broadcast)
2. It is a kind of software for processing pictures, called PHOTOSHOP.
3, PS refers to Sony's game console play station.
4. PS refers to politics, that is, "politics", which is a branch of science;
In fact, there are many more, so I won't list them one by one.
But because it is in your friend's QQ signature, it should refer to the first kind, remarks and supplementary explanations.