How many attributes an entity have?

How many attributes an entity have? how many we have disscusse about the entity give a example

An entity may have many attributes but remember that the identification of attributes should be very relevant to the given scenario.

For example Student is an entity that may have many attributes like age, name, id, courses, sessions, grades, address etc......it seems all said attributes are relevant in the given perspective.
Now, no of friends, habits, interests, details of family, etc are all these attributes related to student but here all these are useless i.e wastage of time and energy.
So, be on track, understand the domain of entity in the given requirements and keep it simple for the identification of attributes.