This is the 10145th most frequent Russian word.
беларусов
The word "беларусов" is the genitive plural form of "беларус," meaning "Belarusians" (people of Belarus).
The word 'беларусов' here is in the accusative plural form, used to indicate the object of the action 'познакомился' (met).
Я познакомился с группой беларусов на конференции.
I met a group of Belarusians at the conference.
In this sentence, 'беларусов' is in the genitive plural form, used to indicate possession or association in the context of the museum's dedication.
Мы собираемся посетить музей, который посвящен истории беларусов.
We are going to visit a museum dedicated to the history of Belarusians.
Here, 'беларусов' is also in the genitive plural form but used as part of 'особенности' (characteristics) to specify the subject being discussed.