(req.body, ' ' , ' ') --> here req is the parameter of your function and using this parameter your can access the properties over then url.
so look this example
suppose this is form 

enter the name : 
 submit  


so if you want to access the name -- which is filled by the user end.
so for this you can 
do like this->   console.log(req.body.name);  -- this will print the name (property) in console.