Brad is correct when he says 'see' in this sense can mean 'to result in' or 'to give rise to' ( in other words be the cause of). It could also mean 'to be the setting or time of'. 'The last fifty years have seen a revolution in science.' Here the last fifty years cannot be the cause, they are the setting or time of the revolution in science. In some cases both meanings work. 'The second world war saw many women take on traditionally male jobs.' Here the second world war could be both the cause and the setting for this situation.

This is a usage that is used more in written than spoken English. It means "resulted in" something.

What "see" means and how to use it in this structure is quite clear from the sentence you gave. I cannot make it any clearer.

'saw'= past tense of 'see' 'to see' an event/something happening. And in this context, 'saw' the growth of many companies' business due to the internet boom.