cata lyst tablue message ? what does mean

[3sem]

vhello friends.
my name is ismail from uae.

i won a bmw car of 325i model 1991 automatic gear.
yesterday. i hit a rock with my car. directly i got this message on the tablue.

( cata lyst )

i found a wire cut under the car. i thought it is from electricty.

could any body know what the message means. and what this wire for ? and wht do i need to do to repair and clear the message ? is this in risk or it is simple and i can continue dreiving with no problem?

all thanks
ismail