How does the typedef struct work syntactically?

I am new to this, so I apologize if I'm being dense. I'm having trouble understanding how to use typedef. Let's say I have the following command:

typedef struct {
    char pseudo[MAX_SIZE] ;
    int nb_mar ;
    } player ;

This creates a type called player which comprises of a chain of characters, and an int, correct?

Now, if we have this line of code:

struct set_of_players {
    player T[NB_MAX_JOUEURS] ;
    int nb ;
    }; 

I don't understand what this does? I would assume it creates a variable of type struct set_of_players, but what is it called? Usually when I see this kind of command, there's a word after the closed amplesand representing the variables name, but here it has nothing; I don't get it. Would this even work if I haven't done a typedef struct for set_of_players?

Finally, I have this line of code that I don't understand:

typedef struct set_of_players players;

I quite honestly have no idea what this even means. I'm assuming this is the typedef that I need to make the previous command make sense, but I don't even know what it does.

Again, I'm sorry if I'm looking at this the wrong way, and for the poor formatting. Any help would be greatly appreciated, thank you.

The typedef statement allows you to make an alias for the given type. You can then use either the alias or the original type name to declare a variable of that type.

typedef int number;

This creates an alias for int called number. So the following two statements declare variables of the same type:

int num1;
number num2;

Now using your example:

typedef struct {
    char pseudo[MAX_SIZE] ;
    int nb_mar ;
} player ;

This creates an anonymous struct and gives it the alias player. Because the struct doesn't have name, you can only use the alias to create a variable of that type.

struct set_of_players {
    player T[NB_MAX_JOUEURS] ;
    int nb ;
}; 

This creates a struct named struct set_of_players, but does not declare a typedef nor does it declare a variable of that type. Also notice that one of the fields is an array of type player, which we defined earlier. You can later declare a variable of this type as follows:

struct set_of_players my_set_var;

This line:

typedef struct set_of_players players;

Creates an alias for struct set_of_players called players. In this case the struct is not defined at the same time as the typedef but is defined elsewhere. So now you can declare a variable of this type like this:

players my_set_var;

Which is the same as the version using the full struct name.