I am new to script
I want to get values from different cells and copy them to another sheet via app script when the user presses the button.
Is it possible?
Here is the Test sheet link https://docs.google.com/spreadsheets/d/1vgd-5jPfjjil2iNcrcfO4awZupqL7m8CofIUMyCWkN8/edit#gid=352097475
So I want the highlighted cell value 
When the user clicks the Add to sheet2
I need to display the cell value from sheet1 to the respective cell in Sheet2
Try this:
function myFunction() {
const ss = SpreadsheetApp.getActiveSpreadsheet();
const s1 = ss.getSheetByName("Sheet1");
const s2 = ss.getSheetByName("Sheet2");
const data = s1.getRange('B2:H10').getValues();
var quantity = data[0][0];
var weight = data[1][0];
var label = data[2][0];
var sheet_name = s1.getName();
var packaging_cost = data[8][3];
var price = data[8][6]
const row = [
quantity,
weight,
label,
sheet_name,
packaging_cost,
price
];
s2.getRange("A3:F3").setValues([row]);
}
Probably you want to use
s2.appendRow(row);
instead of the last line in the code. It will append a new row on Sheet2 every time you run the code.