That is, some branches of the tree that may lead to the model overfitting are cut off.

这就是说，树的某些导致模型过拟合的分支将被剪掉。

As an aside, some machine learning techniques use a fourth set of data, called a validation set, which is used during training to avoid overfitting.

另一方面，一些机器学习技术使用第四种数据集，称为验证集[validation set]，它被用来在整个训练期间避免过适合[overfitting]。