Hazelnut Bush Size and Care
You should ask your friend where she got her plant to give you an idea of whether it is a wild native, a European variety or a cultivar of some type. (Most of those grown as crops for human consumption are European and in our area a disease called filbert blight is a problem, though Rutger's Univerisity is working on a fix).
Our native American hazelnut (a.k.a. filbert) is not as affected by the disease and can grow to 12 feet or more and 10-12' wide. They can spread to form thickets, which are good windbreaks and they have good wildlife/songbird value.
This shrub is not high maintenance, and is best suited to an informal place like dry woodlands, forest edges, fencerows, etc where you'd allow it to grow. If you have an area like that you don't necessarily need to prune.
If you are trying to get nuts, you need more than one plant for better pollination as they are self-sterile. They need full to part sun with a dry or moist soil with a pH of 6.1-7.5.