Learn Polish: Jakakolwiek by była pogoda, nasza ekspedycja pływa po oceanie. - Whatever the weather might be like, our expedition sails around the ocean.

This is a key feature of universal concessive clauses (phrases meaning "whatever might happen"). After a -kolwiek word, Polish uses the conditional mood to express this idea. The conditional is always built using the particle by plus the past-tense form (the l-participle, here była). Even though it looks like the past tense, it expresses a hypothetical or general state: "whatever the weather might be."

Could I attach the particle by directly to the verb, as in jakakolwiek byłaby pogoda?

Yes, but writing it as a separate word right after jakakolwiek is very common and sounds highly natural. The particle by is a "clitic", meaning it likes to latch onto the first stressed word in the clause. While jakakolwiek byłaby pogoda is grammatically correct, pulling by to the second position (jakakolwiek by była...) is exactly how native speakers usually structure these "whatever/wherever" phrases.

Why does jakakolwiek end in -a here?

Jakikolwiek acts like an adjective, so it must agree in gender, number, and case with the noun it modifies. Since it modifies pogoda (a feminine noun in the Nominative case), it takes the feminine singular Nominative form jakakolwiek. If it were modifying a masculine noun like problem, it would be jakikolwiek by był problem.

Why does the sentence use pływa instead of for "sails"?