If a language has no word for a certain concept, then its speakers would not be able to understand this concept.
Sapir-Whorf hypothesis:
a hypothesis, first advanced by Edward Sapir in 1929 and subsequently developed by Benjamin Whorf, that the structure of a language determines a native speaker’s perception and categorisation of experience.
Language is used for organising and communicating thought. Language is partly a reflection of how we think, partly an influence, and sometimes, a limitation on how we think.