Thank you for the reply @Jey-Cee
Is there some documentation or blog that explains how to do that?
Moreover, is there a device that I can use without writing script or complex stuff?
I have just installed the iobroker and don't know and how to learn or start as some parts of the docuemntation are missing.
I wanna try the platform with simple device and simple stuff such as turn off and on the device.

@Jey-Cee When the dashboard is opened in the browser, I selected instances from the navigation bar, then clicked on discovery.0 option
After that, I checked the Serial checkbox and clicked the DISCOVER button. The only result shown is web.0 instance. However; this result is shown even if my Arduino is not connected to my PC.

Please look at the pictures below.

Regarding your question, in Arduino IDE, I can write code to switch the Arduino builtin LED off or on.
I wonder if I can do the same in ioBroker platform, maybe without writing a code, or if necessary, with code.

I have connected Arduino UNO to my PC through USB cable, but I wasn't able to discover it nor the LED built in it. I used serial option for that, the same way we use in Arduino IDE.
I want to control the LED in order to learn how to use the ioBroker platform.

I was able to run programs on arduino using the Arduino IDE so there is no problem in connectivity to my PC

Could you please provide me with instructions of how to discover the device or the LED

More info
Machine: PC
OS: Windows 10
Browser: Chrome
NodeJS: v10.15.0

Thanks