you image is like o_0 enormous. incredibly huge.
I can sort of see what you’ve got tho. You need to create faces to fill it. this is sort of a weird shape, so i dunno if beautify fill will work or not, but you can always give that a shot. Save it before you do, tho :P.
Save it to a new copy, then try this: Tab into edit mode, select all the verts, then hit F, a little popup should appear with some selections “Auto, Make F-Gon, Skin Faces/Edge-Loops” Try that bottom one, “Skin Faces/Edge-Loops”
If that doesn’t work, try auto, or you can press ALT+F to try Beautify Fill. Occasionally those won’t really do anything for me… but then i;m not really a master at that sort of modeling. I pretty much just extrude and tweak Anyway, just try one of those, if it doesn’t work you can always re-load your save or undo and try one of the other ones. If all else fails you can do it manually by selecting 3 or 4 verts to make a triangle or quad, then press “F”. if you only have 3 or 4 selected at a time it should just fill it instead of pulling up the menu.