Yes, it means to do 11 double crochet stitches in the ring you just formed from your first chain stitches, or sometimes around a plastic ring (not many patterns do that, but it's handy to know.) The directions usually say something like "ch 4, join to form ring, ch 3, 11 dc in ring." In that case, you chain four, slide your hook through the very first chain stitch up by your beginning yarn "tail", chain three (those stand in for a double crochet) and make 11 double crochet stitches around the four first chains, rather than trying to put double crochets in each stitch. Now, if you really wanted to do that, you could, by putting more than one dc in each chain, but 99% of the time you just crochet over the whole chain. When you look at the work, you'll see a smooth curve around those first chain stitches.
There are some good videos over on Crochetville.org if you can get there.