Pattern instructions

Hi, I am new to this forum. I have been knitting simple projects for several. years, but this time I took on a sweater and I am confused by the instructions. All three pieces (two fronts, and back) are knitted together on circular needles. When you reach the armholes you dived the knitting into three parts and begin to bind off for the armholes. This is where I am confused. For the left front it says:

Cast off for armhole on alt rows further 2 sts 2 times and 1 st 2 times, but at the same time, when 4 cast-offs have been worked, work the next wrong sides as follows:

I don’t understand the same time part and the 2 sts and the 1 st cast off. It is very confusing to me. Any help would be very much appreciated.
Thank you so much.

Welcome to KH!
Good for you for starting a sweater.

These directions are for the left front (as you would wear the sweater). Cast off at the beginning of the right side rows (RS or public side) of the front.
On row 1 cast off 2sts, work to the e nd of the row, turn, work back, turn to the RS, cast off 2 sts at the beginning of row 3 and finish the row. Now 4sts have been cast off and you’re ready to work the wrong side (WS or private side of the front) row. Follow the directions for this WS row.
When you start rows 5 and 7, cast off one stitch at the beginning of these RS rows.

Now it makes sense. Thank you so much for your quick and clear response. I will give it a go.

Thank you again.