Having read your previous posts, this and the others are pretty clearly test or interview questions. In particular, this question is extremely basic, and something you would already know if you had been using LR for even a short while. Some of your other questions, on the other hand, are advanced.
As you are probably aware, we discourage such questions ehre, and you probably got past us by your slightly fractured English, masking the fact that the questions came from "outside" not from your own inquiries.
I'll take your word for it. But, nevertheless, even if you have only been using LR for a short while, parameterization and its uses would be familiar to you.
In the "Creating Virtual User Scripts" manual there is an entire chapter called "Defining Parameters." (That's what it's called in the 7.51 manual. I haven't checked the one for 7.8).
Regarding the liguistic angle - I'm not objecting to your English. It's simply that your grammar is slightly "off," indicating that your questions are NOT direct copies of test or interview questions [as posed by a native English speaker].