What is solve the problem guys

We have no access to your code: without that we can't be at all specific about a problem.

So ... generic information is the best we can do.
Start by looking at the message - it is trying to be helpful!

The type or namespace name 'Player' could not be found (are you missing a using directive or an assembly reference?)

That's very specific, and it means exactly what it says - it cannot find any type called Player in the current namespace, or any namespace referenced by a using statement in the current file, or a namespace called Player in a separate assembly that is referenced by your project.

So look for the Player class definition and when you find it, check and add references or namespace using statements as appropriate.

You should expect to get syntax errors every day, probably many times a day while you are coding - we all do regardless of how much experience we have! Sometimes, we misspell a variable, or a keyword; sometimes we forget to close a string or a code block. Sometimes the cat walks over your keyboard and types something really weird. Sometimes we just forget how many parameters a method call needs.

We all make mistakes.

And because we all do it, we all have to fix syntax errors - and it's a lot quicker to learn how and fix them yourself than to wait for someone else to fix them for you! So invest a little time in learning how to read error messages, and how to interpret your code as written in the light of what the compiler is telling you is wrong - it really is trying to be helpful!

So read this: How to Write Code to Solve a Problem, A Beginner's Guide Part 2: Syntax Errors[^] - it should help you next time you get a compilation error!