I have got a hand on this PhotoMos Relay AQV201.

How to know whether it is working fine or not?

 

I have got a hand on this PhotoMos Relay AQV201.

How to know whether it is working fine or not?

To verify if the device is working you will need a voltmeter and a power source. But since you only show us the connections and not the specifications that is about all the help I will provide, since I am not going to research and find the rest of the information.
Do you have access to a multimeter??

 

I usually use a load too. Sometimes the relay conducts voltage but not enough current.

 

I have got a hand on this PhotoMos Relay AQV201.

Tip:
They can be used in sink or source output mode.

 

YOU WILL need to know and understand the specifications to verify the correct operation. An easy test is to use a incandescent light as the load, along with the correct voltage power supply. The same supply, with a suitable series resistor can also supply the current for the internal LED, and by observing the light and the voltage across the LED you will be able to verify the correct functioning.