Attributes are the properties (aka data or variables) that represent the current state of the object.
For example, there are many people, so to describe one particular (instance of a) person, we might use their name, e.g. David. If further granularity is required, for example if there were more than one person whose name was David, we might then use further information about that person such as their age, or where they live, etc.
These variables are specific to that instance of the object.
Data stored within an object represents the state of the object.
In OO terminology, an object's data is referred to as its attributes.