A sanction is a punishment or a penalty. There are different types of sanctions that can be applied for different types of reasons.
In the context of the law, judges often provide financial sanctions on parties who violate court regulations. For example, a person who is found in contempt of court may be given a financial sanction and be forced to pay a fine.
Sanctions are essentially a way for the court to punish people who violate court rules. Sanctions can also be put on attorneys who make certain violations as well.
The term "sanction" as a verb also means to authorize something. For example, if a person or a party has been sanctioned to do something, it means that they have been granted authorization to to carry out that specific action.