The problem is that you are allowing the users to go back in your program. If they answer "yes" to the first two questions and then go back to the first one to change the answer to "no", the variable "languagesSpoken" is still 2. Then they answer yes to speaking Spanish and German, so the final value of the variable is 4.
You can try this code instead:
*question: Do you speak French?
>>speaksFrench = 1
>>speaksFrench = 0
*question: Do you speak Spanish?
>>speaksSpanish = 1
>>speaksSpanish = 0
*question: Do you speak German?
>>speaksGerman = 1
>>speaksGerman = 0
>>languagesSpoken = speaksFrench + speaksSpanish + speaksGerman