Standard deviation can be both, positive and negative.
The closer the standard deviation is to 0, the lesser the variability in your data 💪
For example, if the mean of a data set is 70 and the standard deviation is 5. That’s fine. It means that most of the values in the dataset are around 5 points less or more than the mean of 70.
But if the standard deviation of the same mean is 20 – this means there is too much variation in the dataset. And the mean might not be a very reliable representative of this dataset as each value of this dataset might be up to 20 points more or less than 50 🧐