Well, I’m not an expert on topology, but does this matter? I guess it depends on what this is. That is a quad, so it’s not a big problem, but I’m not sure if it’s good topology. You could cut another loop into the rest of your model so that you have nice consistent flow, if you wanted to.
Can we see the rest of the model and where this is located? Is it a hard surface? or organic shape?
I don’t understand what you are asking. could you supply more information, please?
(edit) is this going to be a shadeless object in a game? because if so, correct topology is not so important.
oh, do you mean it doesn’t make a face when you try to fill that area? that happens when the vertexes are too skewed. you can use triangles, or try to level it out.
Delete the edge loop I circled in purple, and then select both verts I circled in yellow and use Alt-M to merge. To fix the matchup, just delete what doesn’t line up on that new outer geometry.
You will need to alt-m the other verts on the other side of that face to join them, essentially deleting a whole face.