The proportion of a room refers to its size and shape - whether it might appear too tall, too short, too wide, too narrow, too large etc...
These can all be big problems in interior design, and are factors that you should consider in your planning and design stage, so that you don't end up with a room that feels dark, dingy and poky, or a room that feels like a cold empty hall, when you just want to sit and relax and feel cosy.
Although the proportions of your room are physical, and you may not be able to physically change these, happily there are interior design tricks and techniques that can lessen their effects, and make your room feel much more 'normally proportioned'.
If you want to find out more about how interior designers deal with problems with room proportion, take a look at my 'Room Proportions section'.
I hope that is helpful for you.
And thanks very much for your kind comments about my site through my 'contact me' page (I am assuming you are the same Patricia?)