It's a participle adjective; an active participle adjective.

这是一个分词形容词; 一个主动的分词形容词。

They can also be active participle adjectives, but I'll talk about that in a second.

他们也可以是主动的分词形容词，但我会稍后谈到这一点。

There are two participles that we need to look at, they are called the active or passive participle.

我们需要注意两个分词，它们被称为主动分词或被动分词。