Hi!
Can I take this issue?

@das-anubhav you're free to submit a PR, sure

Hey, I know python and C++ very well. Is my skills fit into this issue ?

In general, this is going to require understanding how interperters work

This issue is arising because you have put the int32 return type for the function but you want it to return an Object datatype. Here you need to add str instead of int32 for dynamic b.
so try this:

#r C:\Python\Python35_64b\lib\site-packages\Python.Runtime.DLL
using Python.Runtime;
dynamic np; using (Py.GIL()) { np = Py.Import("numpy");};
using System.Collections.Generic;
using System.Collections;
dynamic a = np.array(new List { 1, 2, 3 });
dynamic b = np.array(new List { 6, 5, 4 }, dtype: np.str);
Console.WriteLine(a.dtype);

try to add str instead of int32 in dynamic b