You are looping over a list of some form of data structure with at least 2 indexes and if the 2nd index is greater than or equal to 1000, you are assigning the value of the first index to the list
thousand_or_greater = []
numerical_list = [['Casey', 176544.328149], ['Riley', 154860.66517300002]]
for each in numerical_list:
x=each[0]
x1=each[1]
if x1 >= 1000:
thousand_or_greater.append(x)
print (thousand_or_greater)
>> ['Casey', 'Riley']
This can be shortened using the following list comprehension:
[x[0] for x in numerical_list if x[1] >= 1000]
>> ['Casey', 'Riley']