This is the 9452nd most frequent Russian word.
упц
"УПЦ" typically stands for "Украинская Православная Церковь" (Ukrainian Orthodox Church).
Here, 'УПЦ' is being used as an abbreviation referring to the 'Украинская Православная Церковь'.
УПЦ — это Украинская Православная Церковь.
UOC is the Ukrainian Orthodox Church.
In this sentence, 'УПЦ' is used as a proper noun representing the organization.
Официальные документы УПЦ хранятся в её архивах.
The official documents of the UOC are kept in its archives.
Here, 'УПЦ' serves as a subject representing the Ukrainian Orthodox Church in the context of its historical aspect.