What is a "Compiler error"?

My game worked fine last time I played, but now it says “Cant play game until compiler erroers are fixed.” What do I need to do

Fix the compiler errors? S:

open the console window (WINDOW → CONSOLE) and fix the errors you will see there
im not sure how this thread belong here but w.e

Welcome to the wacky world of programming! The “compiler” is the part of Unity (and of any programming language) that translate your code into ones and zeros that the computer can understand (“machine language”).

So if your code is something like “var target = transform.position + Vector3(1, 0, 0);”, the actually instructions that your CPU understands is something more along the lines of “Add 1 to [random point in memory], then store the result in [another point in memory]”. (Except that’s all in ones and zeros and I don’t actually know machine language :P)

In your case, a compiler error usually means that you made a mistake while writing your code and the compiler can’t make any sense out of it. Think about it like this: Imagine I asked you “Has anyone really been far even as decided to use even go want to do look more like?”
That sentence violates pretty much every rule of English and thus has no discernible meaning. There’s no possible way for you to know what I meant, so you say “What?” That’s pretty much what a compiler error is: the computer is telling you “Dude, you’re making no sense.”

To fix the problem, click on the red error message in the status bar and look at the list of errors that pops up in the console. They’ll describe where the computer is getting confused. Note that they don’t always tell you what’s wrong or how to fix it - they only tell you why the compiler can’t understand it.