What is it called when the government takes money from the rich and gives it to the poor?

Yes. It is called taxation. The government collects income tax, social security tax, Medicare tax, corporate income tax, death taxes, property taxes etc. from people who have money sometimes called rich people. Then the government gives that money to other people who don't pay taxes in the form of social security, medicare, medicaid, earned income tax credits, tuition tax credits, education grants, unemployment compensation, section 8 housing vouchers, etc.

To pay taxes you have to earn money. "Rich People" are anyone who earns money unless you want to start dividing the US population into poor, middle class and rich people. In that case, the middle class pays the taxes as this includes everyone up to $250k per year and the rich people hire attorneys to figure out how to pay as little tax as possible.

As a note, everyone who has a paycheck pays social security and medicare taxes. Only 50% of people with a paycheck pay income tax now. Corporate income tax is collected from corporations but is really paid by the consumer in the form of higher prices. Death taxes are only paid by the super rich but they have ways around this. Property taxes are collected at the state and local levels from any property owner which means owning a car or house causes you to pay taxes.