(Question)
It appears that the spherical objects do not belong to the plant. What are they, and are they harmful to the plants?
Thanks.
(Answer)
The picture is somewhat distorted, but it appears that there are galls on the leaves. Grape vines are susceptible to severe damage caused by a small aphidlike insect, Grape Phylloxera, Daktulosphaira vitifoliae,
Here is an excellent fact sheet from the Canadian government, which includes images and detailed descriptions.
There is another insect which can be confused with this, Erineum mite (leaf blister mite), and it is described in this Government of BC publication on the subject.
I would suggest you review both these resources and examine your plants carefully to see if either of these insects are your culprit.