is this ABS sensor? It was just hanging there like that since I got it..

is this why my ANTI LOCK light is constantly on all the time?

Where should I put it? I have looked around but coundn't find where to put this in!!

 

I have looked at part images for ABS sensor unit. and seems like it's not the abs sensor.
then what is it?

and why my ABS light is on? I want to do ABS blink test
but I am not sure How to do it exactly as I coundn't understand the guide..

could anyone can teach me how to do it easily?