Python vocabulary trainer for terminal
Currently your code is all over the place. You have global variables (which should be named in ALL_CAPS according to Python's official style-guide, PEP8), functions which modify these globals, then some actual code in between the functions and at the end some code that actually executes the code, also in the global namespace (preventing you from importing any of the functions defined here in another script).

In addition I would also change:


Use random.choice(entries) instead of random.randint(0, len(entries)).
Make Entry a collections.namedtuple (which allows using tuple unpacking).
Since you say you are using Python 3.x, use the new f-strings introduced in Python 3.6.
Where this is not possible, use str.format instead of building the strings using addition and manual calls to str.
Make main take the file path (defaulting to the global constant) so it is more extendable.
Making sure to close all opened files again using with ... as.
Use if __name__ = "__main__" guard to allow importing.
Call strip on the manually entered words, removing the need to do that every time you compare them later.
Remove the wrong variable, it is unused (and can be easily calculated as total - right).
raw_input is not called that anymore in Python 3. It is now called input (and the input from Python 2 is gone).




import random
import os
import sys
from collections import namedtuple

FILE_PATH = "./words.txt"
Entry = namedtuple("Entry", ["french", "english"])


def insert(entries):
    while True:
        french = input("French word: ").strip()
        if french == "#":
            return
        english = input("English word: ").strip()
        if english == "#":
            return
        entries.append(Entry(french, english))


def query(entries):
    total, right = 0, 0
    while True:
        word_pair = random.choice(entries)
        french = input(f"French translation of {word_pair.english}:")

        if french == "#":
            percentage = (right * 100) / total
            print(f"You answered {right} question out of {total} correct.")
            print(f"Percentage: {percentage} %")
            return
        total += 1
        if french.strip() == word_pair.french:
            print("Correct.")
            right += 1
        else:
            print("Wrong!")


def printall(entries):
    if len(entries) == 0:
        print("No words stored.")
        return
    for word_pair in entries:
        print("{} : {}".format(*word_pair))


def backup_wordpairs(entries, file_path):
    with open(file_path, 'w') as words:
        for word_pair in entries:
            words.write("{},{}\n".format(*word_pair))


def main(file_path=FILE_PATH):
    if os.path.isfile(file_path):
        with open(file_path) as words:
            entries = [Entry(*map(str.strip, line.split(",")))
                       for line in words]
    else:
        print("File does not exist")
        sys.exit()

    while True:
        command = input("Please enter a command: ")

        if command == "add":
            insert(entries)
            backup_wordpairs(entries, file_path)
        elif command == "test":
            query(entries)
        elif command == "list":
            printall(entries)
        elif command == "end":
            break
        elif command == "reset":
            entries.clear()
            if os.path.isfile(file_path):
                os.remove(file_path)
        else:
            print("No known command.")

    print(" ------- Vocabulary becomes terminated. ----------  ")
    sys.exit()

if __name_ == "__main__":
    main()


As you can see now, almost all functions take entries as the first argument and modify it somehow. This should tell you that you could easily make this a class.