They’ll reinvest a good chunk of it back into their businesses. That means more hiring, more money in their employees’ pockets to spend means more money flowing into the economy. Some will go into new equipment, etc, benefiting suppliers.
Look at it this way. Your employer pays you. Then you pay other people—the mortgage company, the grocery store, your wife’s hair stylist and on it goes.
Then they turn around and pay people. It just keeps flowing to the benefit of many.
Simply put... “a rising tide lifts all boats”
This, of course, is what democrats dismiss as "trickle down" economics. They prefer "investing in our people," by which they mean higher food stamp and other welfare benefits, which produces greater sales of twinkies and soft drinks at the corner store, higher drug sales, more bling for the dealers, and even more welfare babies in the next generation, which democrats call "growing the economy at the grassroots."
Trickle down works both ways. It's just a question of which future America you want to build.
Let's say a US company that used to manufacture in the USA and off shored gets incentivized to "repatriate" profits. Well if all of their production facilities are overseas then just how do they reinvest in the USA? The answer is THEY CAN'T.
Maybe new carpet and chairs for the corporate office but that is about it. All of that money will be pumped into the stock market and real estate.