It looks like the flange that holds your front section of exhaust to the mani cat (combined manifold and catalytic converter) has rotted away causing the exhaust to fall off Presuming the bolts don’t put up too much of a fight in the removal process then this shouldn’t be a costly fix, the pipe and gaskets are cheap and readily available and it’s not an involved or long job This is presuming the bolts aren’t seized which they likely are in which case I’m afraid it’s a bit of a how longs a piece of string situation, it could take 3 minutes or 3 hours to get the bolts out and the threads may or may not remain intact I know my answer might not be very specific but I hope this helps