<?php

$myArrayTwo = array(
        "firstArray" => array(
            "FName" => "Sudhir",
            "firstLName" =>"Gour",
            "firstAge" => 32
            ),
        "secondArray" => array(
            "FName" => "Kartik",
            "secondLName" =>"Sharma",
            "secondAge" => 53
            ),
        "thirdArray" => array(
            "FName" => "Vishwas",
            "thirdLName" =>"Kumar",
            "thirdAge" => 76
            ),
    );
    
    print_r(array_column($myArrayTwo , "FName"));