You attached an external reference (Xref) to your drawing, and it came in skewed or crooked.
If you have a User Coordinate System set as active, any Xref you attach to your drawing will use that UCS as the origin (0,0) for its insertion point and won't recognize the World Y axis. As a result, the Xref will come in skewed.
Before attaching your Xrefs, use our Restore UCS tool to restore the WCS. Once you've attached all your Xrefs, you can restore your UCS again.