"Hint that ___" means to say things that make people guess that you are thinking a certain way.
For example, if Sony "hinted that" they were introducing a new tablet computer, it means that the company hasn't directly stated that they are releasing it. But they have said other things, like:
We're releasing a new product that will give Apple something to consider.
Since one of Apple's most popular products is a tablet computer, it seems that Sony might be talking about competing with that product.