This is the 253rd most frequent Japanese word.
入り
"入り" (iri): Entry; entrance; the act of entering; contents.
Here, 入り (iri) is part of the verb 入る (hairu), which means 'to enter', showing its usage as an action.
新しい店に入りました。
I entered a new shop.
In this case, 入り (iri) refers to involvement or participation, demonstrating a noun usage.
会議にすぐ入りが必要です。
Immediate participation in the meeting is necessary.
Here, 入り (iri) implies 'containing' as a suffix, indicating the inclusion of something.