Nominalisation makes a text sound more academic. Here's an example sentence without nominalisation:
House prices have been rising steadily in the UK and this has caused difficulties for young people trying to get onto the housing ladder.
This example sentence has the same meaning but with a nominalisation at the beginning:
The steady increase in UK house prices has caused difficulties for young people trying to get onto the housing ladder.
Nominalisation means changing a VERB into a NOUN phrase:
House prices have been rising steadily in the UK.....
The steady rise in UK house prices .......
This means that you build a long NOUN phrase at the start of the sentence. Here are some more examples:
Interest rates have been low and this has fuelled the housing market.
Low interest rates have fuelled the housing market.
The government has introduced a help-to-buy scheme which has also been blamed for causing price rises.
The introduction of the government's help-to-buy scheme has also been blamed for causing price rises.
When you use nominalisation your writing has better academic style. You can fit a lot more information into your sentences - it is an efficient way of writing!
If I was a student wanting to improve my ability to write using nominalisations then I would follow this link to the excellent exercises on this feature of academic English provided by Queen Mary University of London here.