help please to understand this pattern

I am knitting the second size and have finished the back piece. I am having trouble understanding these directions for the left front… I understand that I will be casting on 15 stitches and then will knit the first row and increase the first stitch on next row which is a purl row. After that I am confused. Can someone help me please. Thank you very much.

LEFT FRONT Using 4mm (US 6) needles cast on 12 [15: 18: 21] sts. Beg with a K row, cont in st st as folls: Work 1 row. Inc 1 st at beg of next row and at same edge on foll 8 rows, then on 2 foll 3rd rows and at same time shaping side seam by inc 1 st at beg of 4th [8th: 8th: 12th] and foll 6th [-: -: -] row. 25 [27: 30: 33] sts. Inc 1 st at side seam edge of – [next: next: 9th] row. 25 [28: 31: 34] sts. Cont straight until left front matches back to beg of raglan armhole shaping.

Welcome to KH!
Is this sweater top down or bottom up? Can you tell us the name of the pattern and provide a link please?
If you call the next row, row 1 , you would increase on rows 1,2,3,4,5,6,7,8,9, 12 and 15. The shaping for the side seam is on rows 8 and 9

The pattern is on love knitting under Elly baby cardigan. I cannot find the link. You would increase on the opposite ends of each of the 8 rows to keep all the increases at the same edge, is this correct?
the part I am confused on in after it states to increase 1 at the beginning of the next row which would be a purl increase on the purl side, correct? and at same edge at the following 8 rows, this is where I am understanding that you would continue to increase on the following 8 rows keeping the increases on the same edge which I believe you would increase on opposite ends of each row to keep the increases on the same edge is this correct?

The next part is where I do not understand where the pattern states then on 2 foll 3rd rows and at the same time shaping side seam by do not understand this and forward of the Left side. hope someone can help. I am wondering if this pattern is going to be over my head. the knitting part is the easy part if I could just understand the pattern. Thank you so much for your help.

Increase on the same edge, not on opposite ends. You want to keep all the increases on the same edge. You’re going to increase at the beginning of the next row, the purl row and then at the end of the next row, the knit row. Keep doing this until you’ve increased 9 times total. So that’s on the row numbers given in my first post. This will make the curve that you see up the front of the jacket.
There are also 2 increases at the opposite edge, the side seam. Those are on rows 8 and 9.
It’s a darling pattern.

okay, I think I understand now. Thank you for your help. Yes I love the cardigan, but the pattern instructions are a little hard for me to understand, what is it exactly that they are saying when the pattern states; then on 2 follow 3rd rows and at the same time shaping side seams could you explain that in easier terms. Thank you!!

You’re going to increase on every row for rows 1-9. The 3rd row from row 9 is row 12. The following 3rd row is row 15.
Make the increases for the side seam on the other edge (the side seam edge) near rows 8 and 9. So for rows 8 and 9 only you’ll increase at the side seam and at the front edge.

Okay now that explains it in simple terms, thank so much for your help.