How do functions work inside while loops

while not valid_space(game_board,move):
            print(f'What is {current_player}\'s move?(1-9)')
            move = input('>')

ALL_SPACES = ['1', '2', '3', '4', '5', '6', '7', '8', '9']

def board():
    board={}
    for space in ALL_SPACES:
        board[space] = ''
    return board

def displayBoard(board):    
    return f"{board['1']} | {board['2']} | {board['3']}1,2,3\n--+---+--\n{board['4']} | {board['5']} | {board['6']} 4,5,6\n--+---+--\n{board['7']} | {board['8']} | {board['9']} 7,8,9"

def valid_space(board,space):
    return space in ALL_SPACES and board[space] == ''

def is_full(board):
    for space in ALL_SPACES:
        if board[space] == '':
            return False
    return True

def updateBoard(board,space,mark):
    board[space] = mark

def isWinner(board,player):
    '''check for winner in all rows,columns and diagonals'''
    return (
    board['1'] == board['2'] == board['3'] == player or 
    board['4'] == board['5'] == board['6'] == player or
    board['7'] == board['8'] == board['9'] == player or
    board['1'] == board['4'] == board['7'] == player or
    board['2'] == board['5'] == board['8'] == player or
    board['3'] == board['6'] == board['9'] == player or
    board['1'] == board['5'] == board['9'] == player or
    board['3'] == board['5'] == board['7'] == player
    )
        



def game():
    print('Welcome to tic tac toe')
    game_board = board()
    current_player,next_player = 'X','Y'
    while True:
        print(displayBoard(game_board))
        move=None
        while not valid_space(game_board,move):
            print(f'What is {current_player}\'s move?(1-9)')
            move = input('>')
        updateBoard(game_board,move,current_player)
        if isWinner(game_board,current_player):
            print(displayBoard(game_board))
            print(f'{current_player} won the game')
            break
        elif is_full(game_board):
            print('It was a tie')
            break
        current_player,next_player=next_player,current_player    
         
game()