If the house next to you were empty, you might wonder if the person who will buy it is a good or bad neighbor. As there is no specific person known yet, that would the "potential neighbor" (possible neighbor). "I hope my potential neighbor won't be a person who plays loud music!"

potential = possible There is no special meaning here. Check the word "potential" in a dictionary.

If you might move to a different house or apartment, the person next door to the house is a potential neighbor.

Well, you just need to know the meanings of "potential" and "neighbour", and then you will have your answer. Use a dictionary!