The reader is immediately taken into this highly visual and symbolic scene. The tigers which Aunt Jennifer creates are topaz in color, that is wine-red, yellowy orange, and live in a green world where their majestic movements express fearlessness. Green is often associated with the season of spring and rebirth. They prance (step high), and are sleek (smooth and glossy) as well as chivalric. Chivalry is an ancient knightly term and means courteous treatment, especially of women by men. So the tigers know exactly what they're doing, being confident and vital, thanks to Aunt Jennifer's skill at sewing.
Second Stanza

The second stanza focuses on Aunt Jennifer's hands. Her fingers flutter, as if she's nervous, or a little feeble, and even the ivory needle seems too heavy as she works the wool. Ivory is a luxury material, from the tusks of elephants. The wedding band (ring) doesn't help either. It weighs heavily on Aunt Jennifer, perhaps as a result of the emotional baggage associated with it via her marriage.

There's a hint of hyperbole here, 'massive' seems over the top for a mere band. The poet is reinforcing the idea that Aunt Jennifer isn't happy; the work is a challenge despite the fact that it allows her a certain freedom.
Note the contrasts between the first and second stanza. The first is vibrant, light and sure of itself whilst the second is uncertain, a little dark and hard work. Patriarchal power is apparent in the second stanza, whilst the first highlights the creative drive of Aunt Jennifer's tigers.
Third Stanza

A shift in emphasis, from the here and now, to the possibility of what's to come. Again the poet concentrates on the hands of Aunt Jennifer, using language that is pretty extreme : dead, terrified, ringed, ordeals, mastered. The hands that have been so creative are now thought of in this negative way. An ordeal implies long term experience so we can take it that this woman had to endure a long suffering marriage, oppressed by her domineering husband.

Even in death the submissive lifestyle she led shows through in her hands, the workhorses of the woman at home. The one redeeming feature of her life however, the prancing, free spirited tigers, will continue indefinitely. This gives a ray of hope for those who see no way out of a relationship. Art can bring a sense of inner peace and instil confidence, however fragile.