In today’s era, C is still considered a universal programming language. It’s commonly used for systems-level programming. By that I mean writing code or programming software which works on a computer’s hardware, for example, writing software to develop a printer driver or disk defragmenter.
C is still in some circumstances “the language of choice in Operating System Development (including all of UNIX)”. It’s desirable to have knowledge of C because many of its concepts are transferable to other programming languages and there will be a need to be able to maintain, modify, and update code in future operations that were executed by C.