In SAS programming, data is organized into tables called datasets that have rows and columns. The columns are called variables and the rows are called observations. There are two types of variables in SAS: character variables, which contain text-based data, and numeric variables, which contain numbers. Character variables are left-aligned and numeric variables are right-aligned. SAS handles missing values in character variables by representing them with a null value, while missing values in numeric variables are represented with a period or dot.