Breakdown of На море были белые паруса.
море
sea
белый
white
на
on, at / by (transport) / to (a place) / to (in answer to)
быть
to be
Questions & Answers about На море были белые паруса.
Why does паруса end in -а if it is a masculine plural noun?
The singular form is парус (a sail). While most masculine nouns take -ы or -и in the plural, a specific group takes a stressed -а or -я instead. Паруса is one of these exceptions, exactly like города (cities) and дома (houses).
Why do we use на море instead of в море here?
Both are grammatically correct but have different meanings. На море means "on the sea" (on the surface of the water, where sails and ships are) or "at the seaside". If you used в море, it would mean physically "in the sea" (in the water, like fish or submarines).
How does this sentence translate to "There were" without a specific word for "there"?
Russian doesn't use a dummy subject like "there" to show that something exists. Instead, existence is shown by the word order. Starting with the location (На море) and putting the verb (были) before the subject (белые паруса) tells the listener you are introducing new items, which naturally translates to "There were white sails on the sea."
Does the adjective белые get a special ending because паруса has an irregular plural ending?