Question related to System.getProperty("ur")

Hi,

I am new to gatling. I am using 2.3.1 version.
I have one simple question, what does these statement mean in gatling?

val ``pause``:` `FiniteDuration ``=` `System.getProperty(``"pauseBetweenRequestsMs"``).toInt.millisecond` private val url:` `String = System.getProperty("url")`

from where does it takes these values?

Thanks,
Rohit