This question already has an answer here:
That little orange thing is the Object Origin of your object. It's 0,0,0 for the local coordinate system in which all verts of the object are kept.
It's the pivot point of the invisible shoe box in which your mesh lies.
When you move verts while being inside Edit Mode, the Object Origin stays where it is and like in this example ends up far away from the mesh.
In the tools to the left, you have the 'Set Origin' button. There you can select one of three choices. Move your mesh to where the OO is, Move the OO to the middle of the verts or place the OO where the 3D-Cursor currently is.
The real problem that you have here is that you probably dove into using Blender without learning the fundamental basics. What an Object Origin is belongs in that category. That will bite you a lot more often if you don't remedy it.