It

[KSSEEJ]

Here is the opening of an article
"It says something about investors' faith in China as the global economic saviour that world markets are in retreat after Beijing cut the country's growth target to an eight-year low.That was not what they wanted to hear amid debt woes in Europe and mixed signals of recovery in the US, which surely have prompted China to lower expectations of its export-led economy"

What do "it" and "something" refer to? Is "it says something about..." a idom?

Thanks for your advice!

[Raymott]

Here is the opening of an article
"It says something about investors' faith in China as the global economic saviour that world markets are in retreat after Beijing cut the country's growth target to an eight-year low.That was not what they wanted to hear amid debt woes in Europe and mixed signals of recovery in the US, which surely have prompted China to lower expectations of its export-led economy"

What do "it" and "something" refer to? Is "it says something about..." a idom?

Thanks for your advice!

'It' refers to "

that world markets are in retreat".

"That world markets are in retreat after Beijing cut the country's growth target to an eight-year low [subject] says [verb]

something about

investors' faith in China as the global economic saviour [complement]"

"It says something ..." means "There is some significance in the fact ..."
For a simpler example: "It says something about your personality that you beat your horse."
This means, "The fact that you beat your horse says something about your personality." And that 'something' is possibly that you are a callous, unfeeling person.

[BobSmith]

[AmE - not a teacher]

Yes, it is idiomatic.

It = world markets are in retreat after Beijing cut the country's growth target to an eight-year low

Something = China as the global economic saviour