What is the Holy Sprit? It is the 3rd part of the trinity. It is inside of you it is the thing telling you what good you shall do. It has many forms such as a dove, fire, water and air here is a little bit of a bible reading.
After Jesus died the Holy Sprit came and gave the disciples the power to talk other languages. Now why did the Holy Spirit do this? because Jesus wanted the disciples to preach the word to the world.