target in cluster analisys (PCA)
Iris data set comes with a label, it is a supervised learning problem. The task is to predict the species of the flowers.

Your problem need not have a label, it really depends on your task and data. If your goal is to predict the gender and you want to see if you can see a pattern in lower dimensional space, you can give it a try to treat gender as a target. 

If your problem is an unsupervised one, You can also just plot out your data and see whether you see any clustering in your dataset. 

Remark: You might want to be careful about the $0$ values, $0$ doesn't mean the movie is good or bad. It really means no feedback.