If you are holding two balloons close to each other and they move away from each other quickly when you let go of them, what can you say about the charges they have?
There are two kinds of electrical charges--positive and negative. Two objects with different electrical charges (one positive and one negative) will attract each other. Two objects with the same electrical charge (both positive or both negative) will repel each other. It sounds like the two balloons in this experiment have the same charge, because they are moving away from each other. To determine whether they both have a positive or negative charge is a different matter.
This webpage might be helpful for you to have a look at, as it offers more in-depth explanations of how electrical charges work to attract and repel. You could also try this experiment at home. Try blowing up two balloons and rubbing them on your hair to give them a charge. Then, place them next to one another--do they attract or repel?
It might be helpful to keep this phrase in mind when talking about electrical charges--opposites attract and likes repel. The same rule applies to magnets, though this is a magnetic charge and the two variants are the north and south orientations.