The 3rd house covers our thoughts and our thinking process. It's about our mental connections, our intelligence, our analytical capacities and our capacity to communicate. What is our intellectual orientation? What is our mental energy level? It's about learning and using languages too.
This house is about our conscious mind, together with our perception of the world around us. How do we observe and grasp situations? How do we defend our opinion or state our case? It's our level of curiosity for knowledge. It also rules gossiping and our internal dialogs.
The third house rules siblings (brothers, sisters, half-brothers, half-sisters) and our neighborhood (immediate environment). It's also about non-philosophical education, which is covered by the 9th house, short trips and transportations. At last, it covers newspapers and breaking news.