Getting a variable from the caller's globals. What is a frame object?

The documentation for the inspect module says:

When the following functions return “frame records,” each record is a named tuple FrameInfo(frame, filename, lineno, function, code_context, index). The tuple contains the frame object, the filename, the line number of the current line, the function name, a list of lines of context from the source code, and the index of the current line within that list.

What is actually a "frame object"? I was hoping to use this frame object to get a variable's value from the caller's globals():

import my_util

a=3
my_util.get_var('a')

and my_util.py

import inspect

def get_var(name):
    print(inspect.stack()[1][0])