In manufacturing, a feature can be described a physically identifiable portion of a part, such as hole, slot, pin, or chamfer. In design, a feature is the same, but means so much more.
Features are there to serve a purpose in the product.
The above features plus many more make up an a extensive database of features that both designers and manufacturers have at their fingertips. By coordinating a role between design and manufacturing, the features can be beneficial to both.