If you're referring to
A is true B is true
that is read "A is true if and only if B is true".
It's the same as saying A implies B and B implies A.
It's also the same as saying statements A and B are equivalent.
There is some additional commentary in remark 1.4 here:
which is a sample page of my book
(see Amazon.com: Topology and the Language of Mathematics: Chris Cunliffe: Books)
which contains a fair amount of material that would be helpful with other questions like this.