During your journey you may find suits of Armor that you can wear. Armor works like so: When you lose Blood, you will be told if you may subtract your Defense rating from the amount of your Blood loss. If the text makes no mention of subtracting your Defense rating from Blood loss (for instance, if you lose Blood due to starvation, or due to a blow to a part of your body not covered by armor), then, of course, you may not subtract your Defense rating from the Blood loss.
The bulk of the Armor will affect the amount of bulk you can carry whether it is worn or simply carried in your inventory. You may only wear one set of Armor at a time, and so you may only receive the Defense benefits of one set of armor at a time. However, you may carry in your inventory as many suits of Armor as bulk permits, if you want to do so.
Your Black Lance Jetpack Infantryman space suit is not a set of armor. It is simply a suit that protects you against the void of space.