Does this mean she blocked my number?

I've been iMessaging my friend all day, (iMessage is text between 2 iPhones) and everytime i do, it says
(Friend) is Unavailable.
(Friend) is not available for iMessage.

You have to have Wi-Fi to iMessage, and I know she has Wi-Fi cuz she was on Instagram all day. Does this mean she blocked my number?

That could mean that your friend is not using Wi-Fi connection it works kinda like Facetime both phones must be connected to Wi-Fi for that to work