The social sciences are basically about people. They include history, political science, anthropology, sociology, and economics.
The natural sciences include physics, chemistry, biology, ecology, climate science, genetics, and computer science. “Natural sciences” is a terrible name because it suggests that the realm of humans is somehow separate from the realm of nature. These are also sometimes called “hard sciences”, which doesn’t make much sense either.
The kind of knowledge that social sciences are
The social sciences mostly do not use the full scientific method. Historians, anthropologists, and sociologists do sometimes come up with theories about how the world works, but these theories don’t tend to be the sort of thing that you can measure, or test in an experiment. However social scientists don’t just slap knowledge together willy-nilly; they do systematic research, collect and organise information, and make careful, methodical observations, which they publish in peer-reviewed journals. A historian might spend countless hours going through all the writings, artworks, and architecture remaining from a particular time and place, and then piece all of this information together in the form of a book or journal article. An anthropologist might conduct hours and hours of interviews with a particular group of people, then write a paper describing how they live.
Economics can seem like a “hard” science because economists do sometimes come up with theories about things you can measure, like a country’s unemployment rate or inflation rate or GDP. However they never seem to design and carry out experiments that would prove their theories true or false once and for all. You often hear economists say things like “free trade leads to economic growth”, but when their predictions go wrong they don’t usually say: “Oh crap, I guess our theory’s wrong after all!” There is usually some wiggle room; some space to argue about how things should be defined or measured, or how results should be interpreted.
This is not because economists are bad at science, it’s just down to the nature of the systems they study. Like other social sciences, economics is basically about how people behave; individual people, groups of people, and institutions. People are the most complicated thing there is, and our behaviour can’t be defined and measured in the way that we can define and measure the behaviour of, say, a water molecule.