A page three girl is a female who models for topless or nude photographs that are printed in newspapers (specifically page 3 of the Britishtabloids). Introduced in 1970 by The Sun, the format has been widely copied.
... an exact translation would be "I pervade all this universe...".
"mat-sthaani" in the second line is a compound
of "mat" (me) and "stha" (standing, staying at) ...