I mention this not to confuse or worry you but to caution you that years from now you may learn that the story has changed - probably only a little and probably only a detail or two. Most of space is a vacuum or to be more precise, most of the universe has very little gas or any other type of matter in it. However, there are places in space where there are considerable amounts of matter. But I'm getting ahead of myself. There are other places all over the universe where material accumulates due to its mutual attraction caused by gravity.
All matter has mass and all masses are attracted to other masses by the force of gravity.
The nebula will be visible to us here on Earth if there are stars in it or near it to illuminate or excited the nebular materials. Otherwise, the nebula will be dark and can only be observed by its ability to block out stars hidden far behind it. The sixth order of magnitude is about as low as you can see with the naked eye on a clear, moonless night, so you may not be able to see the star at the top of his sword. On a very clear night you can barely see a fuzzy image for Trapezium . Here's some advice to help you see very dim objects.