I have a question: I'm trying to crochet a birthday present for my step mum, it's a scarf, the first row is:

Ch 41, 3 dc in 4th chain from hook (first 3 chs count as first dc), sk next 3 chs, [(sc, ch 3, 3 dc) in next ch, sk next 3 chs] across, sc in last chain, turn.

My questions is I get what's said in the first set of brackets about the first 3 chs counting as first dc but what about the second set of brackets? Can anyone help???