When grapes are pruned while actively growing very early in the year, the cut vines will drip clear fluid.
Some people are still concerned that the vine is "bleeding," which would have a negative effect on the vine. Instead, the dripping tells us the roots are functioning well; they are absorbing water from the ground,
If you are growing grapes, it's likely "Growing Table Grapes" will be useful for you. Download it from https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1639.pdf