This is the 17622nd most frequent Korean word.
세입자들이
"Tenants" or "renters."
The word '세입자들이' here refers collectively to tenants (multiple individuals renting accommodations) who performed the action of paying the rent on time.
세입자들이 집세를 제때에 냈어요.
The tenants paid the rent on time.
In this sentence, '세입자들이' again refers to tenants collectively, who were expressing dissatisfaction with the contract terms.
세입자들이 계약 조건에 대해 불평을 했습니다.
The tenants complained about the terms of the contract.
Here, '세입자들이' signifies a grouping of tenants intending to have a meeting with their landlord.