This is the 5782nd most frequent Russian word.
профсоюзов
"Профсоюзов" means "trade unions."
Here, 'профсоюзов' refers to trade unions in general as the subject of the sentence.
Уровень участия в профсоюзов вырос за последние годы.
The level of participation in trade unions has increased over the past years.
In this sentence, 'профсоюзов' specifies the collective group of trade unions organizing a meeting.
Собрание всех профсоюзов состоится в пятницу.
The meeting of all trade unions will take place on Friday.
The word 'профсоюзов' here emphasizes the functioning and activism of trade unions.