I have been looking at this row for ages and just cannot work out how to do it can someone please help it’s driving me mad.

Cast on 148 stitches
1st row. K3 * p2, k2 rep from * to last st, k1
2nd row k1, p2* k2, p2 rep from * to last stitch, k1

These two rows form rib
Work in rib for a further 5 rows ending with a RS row.

This I have completed and it Is the next row which has really confused me.

8th row rib 6, ( rib 1, rib 2 tog, rib 3, rib 2 tog tbl, rib 1) 15 times,rib 7. 118 sts.
If anyone could please spell out to me what I need to do I will be very grateful
Thank you

Welcome to KnittingHelp!
The pattern is telling you how and where to decrease across the row. Some of the decreases will use two knit stitches and some will use a knit and a purl stitch. The instructions are telling you how to do the decreases, straight work2tog or work2tog tbl (through the back loop) depending on which sts are worked together. Just follow the directions across the row. For example:
Row 1 k3, p2, k (that’s the rib 6), k (that’s the rib 1), p,p (that’s the first work 2 tog, so purl 2 together), k,k, p (that’s rib 3), p,k (that’s the work 2 tog tbl) and so on.
You might write the repeat in parentheses down a column and check off each set of sts as you do them.