Finding an equilibrium of an index of an array
You can utilize built-in features of Python to refactor the code. 


Use the sum() function   

Python already provides a sum() function to add all elements of a list that you can use.

example_list = [1, 2, 3, 4, 5]
result = sum(example_list)

Slicing   

Python allows selecting a range of values of a list. The syntax is:

list[start:end:step]


All these are optional. By default, start is 0, end is the length of the list, and step is 1.

Using this, you can select elements before the index by list[:index] and select elements after the index using list[index+1:]. 
Idiomaticity

Here, a and b are compared for equality. If a is equal to b, the expression a == b will be True, so True is returned.

if a == b:  
    return True

# Refactored
return a == b

Naming conventions

snake_case is preferred over camelCase for naming in Python community. Use is_equilibrium instead of isEquilibrium.