Help with boundaries on imported models

Alright, I am a complete beginner. So please keep that in mind when answering and please state the correct terms!

Question:

I made a nice house in Blender and exported the FBX and everything looked fine… until I tried to go inside of it. It was like there was a boxed invisible wall around it. How can I set the boundaries to be at the walls?

Please answer in the noob format!

Take a look at this tutorial and choose one way: :slight_smile: -> you have to create a proper collision for your mesh