This is the 7371st most frequent Russian word.
главное
The main thing; the most important.
'Главное' is used as a topic marker indicating a key aspect or focus of the discussion.
Главное, чтобы все были довольны.
The important thing is that everyone is happy.
'Главное' is used as a noun meaning 'the main thing' or 'the priority'.
Главное - это держать позитивный настрой.
The main thing is to maintain a positive attitude.
'Главное' acts as an adjective meaning 'main' or 'primary'.