He says this in Chapter 7 when he is trying to explain to Gatsby why Daisy is in love with him. Tom is angry and jealous of Gatsby and believes that Daisy's love for Gatsby is based on Gatsby's wealth and lavish lifestyle, not genuine affection.
The quote reveals Tom's cynical and materialistic worldview. He sees Daisy's love as something that can be bought and sold, like insurance against a fire or flood. This is in stark contrast to Gatsby's romantic and idealistic view of Daisy, who he sees as a symbol of his lost love and the American Dream.