Help with decreasing instructions please!

The pattern I have states "work 6 rows dec 1 st at each end as before in 3rd row"
I’ve just set raglan shapings with the last four rows (1st and 2nd row cast off 3 stitches, 3rd k1 s1 k1 psso only to last 3 st k2tog k1, 4th purl) so does it mean follow what I did on the 3rd row?

Yes, you’ve got it. The decreases are as row 3, one at each end. The WS rows are the purl rows so all your decreases are on the RS rows.