In the US, they use the term 'Gross National Product' (GNP) while, in the UK, we call it the 'Gross Domestic Product' (GDP). They both refer to the same thing. It is simply the monetary-value of the total national production. Its trajectory and its ups and downs over time are often used as a significant indicator of national "success"; how well we are doing. But listen to Robert Kennedy on the subject. He was pitching for the Democratic presidential nomination in March 1968.
" It (the GNP) counts napalm and counts nuclear warheads and armoured cars for the police to fight the riots in our cities. It counts --- the television programs which glorify violence in order to sell toys to our children. Yet the GNP does not allow for the health of our children, the quality of their education or the joy of their play. It does not include the beauty of our poetry or the strength of our marriages, the intelligence of our public debate or the integrity of our public officials. It measures neither our wit nor our courage, neither our wisdom nor our learning, neither our compassion nor our devotion to our country. It measures everything, in short, except that which makes life worthwhile. And it can tell us everything about America except why we are proud to be Americans."
He was assassinated three months later!