How to get particular part of image using json? java android

Question

I am new to Java android game development and I am learning it from past few days, so to learn it i used github scripts to understand how an java game project work than i went to this image which is in res directory: Elements of the game

and this json file with same name as image only diffrence is extension:

"frames": {
    "bg_shadow.png": {
        "frame": {
            "x": 792,
            "y": 712,
            "w": 60,
            "h": 60
        },
        "rotated": false,
        "trimmed": false,
        "spriteSourceSize": {
            "x": 0,
            "y": 0,
            "w": 60,
            "h": 60
        },
        "sourceSize": {
            "w": 60,
            "h": 60
        }
    },
    "button_black.png": {
        "frame": {
            "x": 398,
            "y": 730,
            "w": 146,
            "h": 44
        },
        "rotated": false,
        "trimmed": false,
        "spriteSourceSize": {
            "x": 0,
            "y": 0,
            "w": 146,
            "h": 44
        },
        "sourceSize": {
            "w": 146,
            "h": 44
        }
    },
    "button_gold.png": {
        "frame": {
            "x": 611,
            "y": 345,
            "w": 146,
            "h": 44
        },
        "rotated": false,
        "trimmed": false,
        "spriteSourceSize": {
            "x": 0,
            "y": 0,
            "w": 146,
            "h": 44
        },
        "sourceSize": {
            "w": 146,
            "h": 44
        }
    },

by opening this json file i understood they are the coordinate of the image with height and width.

I just want to know any way to change the icons from image and any suggested tutorials for this

Thanks in advance