What does it mean to sing with space?

Question

And how do you do it?

Answer 1

trouchpet has half of it right, as far as the upper portion of space is concerned. Another area is below the base of the tongue, where all the muscles are under your jaw. This area, known as the pharynx, is a hot bed of muscular energy. if you make enemies there ( your tongue bunches up, gets tight, you feel tight under your chin, your jaw is clenched, etc) you're going to be pushing and forcing your voice through.
Take time and give a yawn. Go on, it's hard not to.
Feel how big, open and easy the space back there was? (BTW, you also felt your soft palate arch upwards, as trouchpet rightly recommends) Now try the inhale portion of the yawn again, and STOP. Can you feel how open you are again?
So, you want to learn how the upper and lower sections of your jaw work. Independently at first, and then work on coordinating the two. of course, here is where a singing teacher is indispensable: he/she will guide you in how these important areas work, and give you exercises aplenty to get them coordinated...
Best wishes and keep on singing

Answer 2

It means to raise the soft palate. Pretend you have an egg in your mouth as you sing. If that doesn't work for you, you can try putting a pencil as far back between your teeth as you can. That would be enough space...some people do the pencil thing every time they practice.

Answer 3

Maybe they meant you should sing IN space.
.