Need Help

Help im new to this, my daughter is expecting her first baby and i would like to start knitting, i have done the back of a cardigan but im stuck on these instructions. I’m knitting the 0-6 months size and it the V-neck cardigan and i’m knitting the right side, ive done up-to for 1st size and 5th sizes only work two rows without shaping.
For all 6 sizes
Work 2 (4:6:2:4:2)rows dec 1 st at neck edge in 0(0:3rd:0:1st:0)row AT SAME TIME dec 1 st at raglan edge as before in next and every foll 0(2nd:2nd:0:2nd:0)row. 16(18:18:22:22:26)sts
Work 18(20:20:26:26:32)rows dec 1 st at neck edge in next and every foll 8th(6th:6th:6th:6th:6th) row AT SAME TIME dec 1 st at raglan edge as before in next and every foll alt rows 4 sts.
Next row k1 k2tog k1 3 sts etc I know that bit
Please help a distressed grandma to be.

Welcome to the forum!
Congratulations on the coming grandchild, the best reason to start knitting.
Whenever you see a zero for your size, skip the step. For the first size, work two rows (rows 1 and 2) with a dec in row 1 at the raglan edge and then dec at the raglan edge in rows 3,5,7,9,11,13,15,17,19.
Dec at the neck edge on rows 3, 11 and 19. That should take you to 4sts.

Thank you so much for the information, really helped.
Would this be exactly the same for the left side x

It should be similar on the left side. The rows might shift one number up or down because the neck and the raglan edges are on opposite sides but otherwise, the same.