How to get a value from related list field

[Venkat141]

How to get a field from below highlighted field.

I tried to use current.test_value but i'm getting undefined. moreover I cannot able to see the field in filter conditions. Please find below snap. Could anyone please help me.

@Ankur Bawiskar 

@Saurav 

@shloke04 

@Anil Lande 

[Ankur Bawiskar]

@Venkat141 

that is a related list table

If the BR is on SC Affected Services table then only you can access the Test Level field value