In Chapter 5 of Rich Dad Poor Dad, Robert Kiyosaki discusses the importance of understanding taxes and the power of corporations in building wealth. He emphasizes the difference in mindset between the rich and the poor when it comes to taxes. The rich use corporations and other legal entities to minimize their tax burden and keep more of their income, while the poor often work as employees and pay higher taxes. Kiyosaki suggests that understanding how taxes work and leveraging the benefits of owning businesses and investments can lead to financial freedom. He encourages readers to educate themselves about tax laws and to seek advice from financial experts to make informed decisions about their finances.