If someone told me they were walking around the house I would assume they are walking around inside the house from one room to another. 'Around the house' often implies doing unimportant activities at home. For example, one might say 'I wear pajamas around the house', here we don't literally mean around the house but rather at home.

Normally it should be walking outside the house, have a tour or something. Would be a bit weird to say someone walks around inside the house - unless one is really nervous or having a panic attack.

It means either. One of the confusing things about English. Hopefully you would be able to figure it out by the context.

Technically it could mean either, but certainly in UK English "walking around the house" would suggest someone is wandering aimlessly from room to room inside their home. Indeed, "house" could mean flat or apartment etc as well. You would only use it to refer to the outdoors if you were :literally: walking around the perimeter of the house, maybe checking for damage after a storm for example. Hope that helps! :)

В США фраза «To walk around the house» означает бродить по внутри дому. Если вы находитесь вне дома, добавьте слово «Outside / снаружи». Например: (Внутри) I was bored, so I just walked around the house for fifteen minutes, looking for something to do. (Мне было скучно, поэтому я минут пятнадцать просто ходил по дому, ища чем заняться.) или (Вне) I heard an animal outside, so I walked around the oustide of the house to see what made the noise. (Я услышал звук животного снаружи, поэтому я обошел дом по периметру, чтобы посмотреть, что производит шум.) Good luck!