We have the senses (eye, ear, nose, tongue etc) right? Now, all these senses are linked with their respective external objects of enjoyments.
These external objects of enjoyments, which the various senses always want to enjoy, are called Vasana or desires.
Like the eyes always desire to see (beautiful) things, the nose wants to smell fragrance, the tongue wants to taste delicious foods, the penis long for sensual enjoyment etc.
So, good view, smell, delicious foods etc are the Vasanas.
The following is Kathopanishad 2.1.1:
Paranchi khani vyatrinat swayambhustasmat parang pashyati naantaratman |
Kaschiddhirah pratyagatmanamaikshad avritttachakshuramritatvamicchan ||
The outwardly-focussed senses are destroyed by Swayambhu (Paramaeswra); Therefore the Jivas see the objects of the outer world and not the inner soul. But, some conscious being, who is desirous of immortality, by controlling his senses, witnesses the inner-soul (antrataman).
(Here khani=senses/Indriya and Paranchi refers to natural outward inclinations of the senses).
If you see, all the senses are naturally attracted to their respective objects of pleasures (Vasanas) and their tendency is to go outward. But in that state the true nature of the inner self can not be realized.
When, Indriya Samyam (subjugation of the senses) is attained and the senses' natural outgoing tendencies are blocked, the inner self is revealed.
Thus, as long as the senses are attracted to their respective Vasanas, true knowledge of self is not attained. This is the purport of the verse given.
So, senses are naturally framed to go outward and they are naturally attracted towards their respective objects of pleasures (or Vasanas). But only if this outwardly nature of the senses can be curbed and if they can be made to focus inwards, one can attain the true knowledge of the self.