To swindle means to deceive or cheat with the intent to gain money or property from the trick or deception. Swindling is a form of theft, and is therefore a crime and illegal.
People who swindle often do so by creating lies or scams that cause people to part ways with their money, when they would otherwise not do so.
Swindling is typically different to straightforward theft. In straightforward theft, a person takes what is not his or hers. However, with swindling, a person tricks another into giving what they ordinarily would not give. For example, a swindler on the street may go around collecting money for a "charity." However, the charity may not be real, and the swindler may then keep all of the money that he or she collected through donations as profits.