This is the 943rd most frequent Japanese word.
やつ
"やつ" (yatsu): A casual or colloquial term meaning "guy," "thing," or "one," often used informally to refer to people or objects.
Here, やつ is used to casually refer to a person viewed in an informal or familiar context.
あいつは強いやつだ。
That person is a strong one.
Here, やつ refers to an object, showing its usage for things in a casual tone.
このやつ、壊れやすいから気をつけて。
This item is fragile, so please be careful.
Here, やつ is used to generalize a noun, serving as a colloquial substitute.