By contemporary Art practice, im assuming it means conceptual (ideas) and material (techniques/actions/material)
So basically the question is asking you how new art ideas or new art practices challenged its time (whether it being unconventional in terms of technique or sending a message that would have been progressive for the time)
For example, consider Duchamp's bicycle wheel or fountain
In terms of material practice, it was quite unconventional for the time where most artists were making highly realistic pieces of work. For bicycle wheel, he literally shoved a stool and bicycle wheel together. As for, the fountain, he literally made an urinal an artwork.
This brings us to conceptual practice, with duchamp creating these artworks to send the message that everyday objects can be raised to the dignity of a work of art by the artist's act of choice.
hopefully this helps