Just like IN (intro) is played once at the beginning, A CODA is plays just once at the end.
The CODA symbol must be placed TWICE.
First, on the last beat of the measure that will precede the start of of the CODA. That tells the player to "jump to CODA, last time"
Second, on the first beat of the CODA (usually written out at the bottom of the chart)
)BOB