First the issue of watching people kiss in TV has already been addressed on the site Is it haram to watch people kiss on TV? so maybe the answers there should be enough to say that this is not allowed. Note that already watching tv per se is considered as a waste of time and hardly permissible (see this fatwa on islamqa).
Also read (24:31)
And tell the believing women to reduce [some] of their vision ...
And the hadith:
Allah fixed the very portion of adultery which a man will indulge in. There would be no escape from it. The adultery of the eye is the lustful look and the adultery of the ears is listening to voluptuous (song or talk) and the adultery of the tongue is licentious speech and the adultery of the hand is the lustful grip (embrace) and the adultery of the feet is to walk (to the place) where he intends to commit adultery and the heart yearns and desires which he may or may not put into effect. (Sahih Muslim)
Which states that watching at what is not lawful (foreign men, women, people being intimate etc.) is a kind of zina. While Allah says:
And do not approach unlawful sexual intercourse. Indeed, it is ever an immorality and is evil as a way. (17:32)
Instead of watching this she should try to get to know her future husband more by meeting him in company of a guardian and exchange questions on each other preferences. This might help her much more to be a good wife than to learn kissing by watching other people kiss on TV (which hardly represents reality or real affection as it should be between spouses).
Maybe this might also be helpful: What is the punishment for kissing someone outside of marriage?