Sampling, as in food, means trying small potions of each food item. It can also be applied to other things as well.
Sampling is a term used in music when someone takes a piece of a song, maybe a chorus or backing track and uses it in a new song.
There have been many examples of this in the past few years, some better than others!
Even famous people with established careers have been known to 'sample' other artists songs, Madonna did it with her song "Hung Up" which takes the backing track from "Gimme! Gimme! Gimme! (a man after Midnight)" by Abba.
Another example is "Don't Stop the music" by Rihanna. The "mama-se, mama-sa, ma-ma-koo-sa" chant is taken from Michael Jackson's "Wanna be Startin' Somethin".
Even the gorgeous Enrique Iglesias has used a sample in his song. "I like it" (which also features Pitbull) has a line from Lionel Ritchie's hit "All Night Long (all night)".
To be honest, sampling often gives the older songs a new lease of life, although in my opinion, it has also been known to wreck them too!
Here is the Madonna video with the sample from Abba.