It depends a bit on how you’ve created the Dataset or the targets in particular.
E.g. if you are dealing with image data (images stored in two folders), torchvision.datasets.ImageFolder will read the data and create the appropriate targets.
You could check the range of the labels by printing them in the DataLoader loop, e.g. simply by:
print(labels.min())
print(labels.max())

If you could post your Dataset, we could have a look at it here.