You can write a program using more than one programming language. For example, you might have some low-level C library that you make use of from a Java program. Since Java doesn't by-default know anything about C, you need some trick to call code written in C from Java. That trick -- when used to interface to some given object code -- is referred to as a language binding. In this case, we say that there are "Java bindings" for some given C library or object code.
Since C is such a common low-level language, and since there is so much useful already-written C code out there, it's very common for high-level languages (like Python or Java) to have bindings for common C libraries.