Books in multiple languages on the same shelf are one of the strongest background signals you can find. People don't keep books in languages they can't read.

What multiple languages signal

Reading the combination

The specific languages matter. French + English + a third language is a strong education signal — France has a strong tradition of intellectual reading. Spanish + English in the Americas suggests immigrant background or dual heritage. German academic texts alongside general non-fiction usually means formal academic training.

One foreign language

A single book in a foreign language is weak evidence — it could be a gift, a souvenir, or a language-learning attempt. Multiple books in a language mean actual fluency.