Working as a secretary

It will be impossible to find a job as a secretary with poor English in Australia.

Many Australian secretaries are unemployed themselves and employers will always give priority to Australians over foreigners for jobs.  Do not expect that she will get a job anywhere - Australia's levels of unemployment are rising and foreigners are the first to lose their jobs.

Ok thank you for the information 

I am afraid my wife gets bored if she doesn't have the chance to work. I am optimistic that she will have an intermediate english by the time we get there, maybe she could study or find a part time job, what do you think?

The chances of her getting a job are zero, if it happens you will be extremely lucky.  Be prepared that your salary will be the only income you have both to live on.  I hope you have a permanent job set up before you travel and its so so expensive to do anything in Australia.

I would have to agree with the posts from Googley2

Secretarial work is something locals can do. Companies will not consider expat workers as the visa process is lengthy and the price is high.

For cost of living try www.numbeo.com