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:

http://www.bobostrategy.com/PartIChapter1.jpg

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.