What does "emit" mean in general computer science terms?

In the context of web and network programming:

When we call a function the function may return a value. When we call a function and the function is supposed to send those results to another function we will not user return anymore. Instead we use emit. We expect the function to emit the results to another function by our call.

A function can return results and emit events.

I've only ever seen emit() used when building a simple compiler in academia.

Upon analyzing the grammar of a program, you tokenize the contents of it and emit (push out) assembly instructions. (The compiler program that was written actually even contained an internal function called emit to mirror that theoretical/logical aspect of it.)

Once the grammar analysis is complete, the assembler will take the assembly instructions and generate the binary code (aka machine code).

So, I don't think there is a general CS definition for emit; however, I do know it is used in the pseudocode (and sometimes, actual code) for writing compiler programs. And that is undergraduate level computer science education in the US.