How is this true? By holding its exchang rate low(China) it is stealing jobs & causing US to run a trade defic

How is this true? By holding its exchang rate artificially low(China), it is stealing jobs & causing the US to run a huge trade deficit.
I was also wondering what a trade deficit is.
Thanks....
It would be great if you could also relate this to the undervalued Chinese Yuan.

It's not really true, the Chinese economy is deftly being run to benefit the Chinese government not steal U.S. jobs and cause a deficit within the states.
"Wishful thinking

The biggest myth of all is that a revaluation of the yuan would greatly reduce America's trade deficit. The real cause of the deficit is that Americans spend too much and save too little. This means that the country has to import surplus savings from abroad by running a current-account deficit. If a stronger yuan did not cause Americans to save more, it would do little by itself to reduce the trade deficit.

Another reason why even a big rise in the yuan would do little to reduce America's deficit is that there is little overlap between American and Chinese production, so American goods cannot replace Chinese imports. Instead, other countries, such as Indonesia and Vietnam, would probably replace the Chinese. Shifting purchases to higher-cost producers amounts to imposing a tax on American consumers, says Stephen Roach, chief economist of Morgan Stanley."
-I got that from this link: http://www.economist.com/finance/display...
So, it's not really China's fault at all, it's the way Americans and their government spend their money is what's causing the problem with their plummeting economy.

Frankie is partly right. Americans are spending beyond their means, which results in more imports of foreign goods than Americans are selling abroad (the US trade deficit).

But the artificicially weak yuan is partly to blame too. When China keeps its currency weak, it results in relatively cheap Chinese goods. This cannot go on forever. Americans will eventually take on so much debt that foreigner will stop lending to them, or the Chinese households will revolt because they cannot afford to buy foreign goods.