The concept of electric potential is based on a positive test charge so when near the positive electrode, it is said to be in an area of high potential and near the negative electrode, it is said to be in an area of low potential. If you a have a negative charge, it will be repelled by the negative electrode and attracted to the positive electrode, so it is said to move from low to high potential (solely because of the definition of potential in reference to a positive test charge). Hope this makes sense!