How steep is a blue run ???

The indoor snow slopes we have bear no real relationship to a real pistes which tend to be steeper, usually wider, vastly longer (which is what we want) and gets bumpier at times.

Providing it's wide enough for you to complete your turns the exact steepness is almost irrelevant up to a point.
Sure looking down will seem a little scary at first but so long as you can link your turns don't get too worried. If you still rely on snow ploughing to control your speed then it's a different matter. (I don't mean plough turns - most of us will have learned to ski starting with plough turns before progressing onto parrallel ones)

A useful tip is to be guided by what you go on during your lessons and to ask your instructor to point out runs for you to practice on (or a friend if they've been there before).

One to watch out for is the run down into the town - many times these will be undergraded to make the resort seem beginner friendly. In reality these are often mountain roads with snow on.
At the end of the day these will be full of spooked novices discovering this "blue" is nothing like the ones up the mountain - particularly if it's warm & the snow gets heavy in the afternoon.