oh forgot about the .*

. means any printable character and * is any number of occurences of the character preceding the *

so s=.*/==' means
s --- search
= --- the separator that i talked before of
.*/ -- occurence of any character (.) folowed any number of times (*) and ending with a slash (/)
= --- replace the above searched pattern with
= --- this is more like a ''= meaning replace with null and end the command

hope this is explainable enough
I would suggest you to study about sed, ed etc to help u understand these things better

warm regards