"string" is an undeclared identifier?

hi, I am making a swimming sport system, but I have a problem.
the issue is that:

FString season = "summer";

gives me “FString is not valid” in output, so I tried

string season = "summer";

and that gave me “string: undeclared identifier”
error is on line: 7
script (numbers on left are not in actual script, only for you to read lines easier):

1. #include "season.h"
2.
3. //correct season function
4. void correct_season() {
5.
6. //season string
7. 	string season = "summer";
8.
9. //if season is spring or summer do
10. 	if (season = "summer") {
11.
12. 	}
13. }
14. correct_season();

FString season = "summer"; is correct; where exactly do you declare it?

line 7

“=” is assignment, “==” should be used to test for equality.

I see #include "season.h", so it must be “season.cpp” file, right?
Are you trying to declare of a string outside a namespace? That’s not going to work. You can either declare it in .h inside UCLASS(), or within a function in .cpp. You can’t declare it in an empty space in .cpp.

that only added another error to my barrage of errors, that error isn’t the only one.

where exactly would i put the string variable:
.h script:

1 // Fill out your copyright notice in the Description page of Project Settings.
2 
3 #pragma once
4 
5 #include "CoreMinimal.h"
6 #include "GameFramework/GameStateBase.h"
7 #include "season.generated.h"
8 
9 /**
10 * 
11 */
12 UCLASS()
13 class NAKED_TOWN_API Aseason : public AGameStateBase
14 {
15 	GENERATED_BODY()
16 	
17 };

I placed:

string season = "summer";

on line 16 and got:

D:\weird games i made\Naked_Town\Source\Naked_Town/Public/season.h(16) : error C3646: 'season': unknown override specifier
 D:\weird games i made\Naked_Town\Source\Naked_Town/Public/season.h(16) : error C2059: syntax error: '='
D:\weird games i made\Naked_Town\Source\Naked_Town/Public/season.h(16) : error C2238: unexpected token(s) preceding ';'

I just change string to be FString in .h file, and it worked!!! (as in i don’t see any .h errors, I only see .cpp file errors) But I still have the “unidentified error” this post was about in the first place.