This is the 18459th most frequent Russian word.
юбилеем
"Юбилеем" (Yubileem) means "anniversary" or "jubilee" in English.
The word 'юбилеем' is used here in the instrumental case, denoting what the congratulations are related to, emphasizing the joyous occasion or significant anniversary event.
Поздравляю тебя с юбилеем!
Congratulations on your anniversary!
The term 'юбилей' refers to a milestone or celebratory anniversary in a general context, specifically tied to the founder in this example.
Сегодня мы отмечаем юбилей основателя компании.
Today we are celebrating the anniversary of the company's founder.
Here, 'юбилеем' is instrumental case highlighting the anniversary in connection with traditions, portraying it as the central theme.