In informal language, it can refer to something insignificant or worthless.

निरर्थक चीज़

English Usage: He doesn’t care a fig about politics.

Hindi Usage: उसे राजनीति की एक भी निरर्थक चीज़ की परवाह नहीं है।

Refers to something that is worthless or of minimal value.

निरर्थक चीज़

English Usage: His arguments were nothing but garbage.

Hindi Usage: उसके तर्क केवल निरर्थक चीज़ थे।