It basically means - you have what most guys want, and from most womens (or mens for that matter) perspective you really don't need to increase anything...
5.5-6in length (Pressed right to the bone) is average length.
4.9-5in Girth is average.
Anyone over 7 in length is longer than 85-90% of men... Anyone with more girth than 5.5 is fatter than 80% of men - and having both together puts you in the top 10% or so.... Of course there are lots of bigger guys about, and it's not like you're HUGE - but you're way bigger than average...
If your flacid is tiny the some light jelqs (newbie routine) for a few weeks will soon sort that out (it seems to increase the blood flow..)