Answer: I need to buy 3 biros. I think the answer provided is incorrect. It should be " I need to buy 3 pens."
Biro is a trade name for a kind of ballpoint pen (invented by a Mr Bíró), which was widely used in the UK for ballpoint pens in general, though not so much now, I think. A bolígrafo is also a ballpoint pen, so it's actually quite a good translation - if you're familiar with the word!
Bolígrafo, biro, lapicero, lapicera... it's a regional thing.
How is a learner of Spanish supposed to learn how to pronounce a word when the person reading your script cannot correctly pronounce "bolígrafos?" The stress on this word is on the letter "I" as indicated by the accent mark. Your reader pronounces the word as "boligrAfos" with stress on the A when the word is correctly pronounced with the stress on the letter "í". Does anyone supervise or edit the spoken Spanish. I think not. Shame on Duolingo!!!!!!!!!
I'm not sure I see the reason for the translator to speak so fast that he's indistinguishable. He runs his words together so fast that I can't understand him. The woman is much easier to understand.