All 3 Uses of

arbor
in
The Mill on the Floss

He got down, and passed with Mr. Moss into the garden, toward an old yew-tree arbor, while his sister stood tapping her baby on the back and looking wistfully after them.
Chpt 1.8 *

arbor = a framework that supports climbing plants; or a shady rest area made by such a framework or by trees and shrubs

Their entrance into the yew-tree arbor surprised several fowls that were recreating themselves by scratching deep holes in the dusty ground, and at once took flight with much pother and cackling.
Chpt 1.8

Mr. Tulliver walked abruptly out of the arbor as he uttered the last sentence, and, without looking round at Mr. Moss, went on to the kitchen door, where the eldest boy was holding his horse, and his sister was waiting in a state of wondering alarm, which was not without its alleviations, for baby was making pleasant gurgling sounds, and performing a great deal of finger practice on the faded face.
Chpt 1.8

Definitions:

(1) (arbor as in: shaded arbor)
a framework that supports climbing plants; or a shady rest area made by such a framework or by trees and shrubs

The framework of an arbor is generally thought of as a wood lattice made to support vines, but it can also be a natural framework such as trees.
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Much more rarely, an arbor can be used as a proper noun to reference a location. As a common noun, it can also reference various types of rotating machine shafts.