more like this?

Later you want to have an array of a class Button or use a lib

1. void setup () {
2.   size (500, 350);
3. }
4. 
   
5. void button (int nr, String text) {
6.   int buttonX = 0;
7.   int buttonY = 100;
8.   int buttonW = 70;
9.   int buttonH = 20;
10. 
    
11.   buttonX = 80*nr;
12.   rect (buttonX, buttonY, buttonW, buttonH);
13.   text (text, buttonX, buttonY);
14. } //  func button
    
15. 
    
16. void draw () {
17.   button(1, "Button1");
18.   button(2, "Button2");
19.   button(3, "Button3");
20.   button(4, "Button4");
21.   button(5, "Button5");
22.   button(6, "Button6");
23. }

the first button needs an x of 10.

ok

Greetings, Chrisir   

1. void setup () {
2.   size (500, 350);
3. }
4. 
   
5. void button (int nr, String text) {
6.   int buttonX = 0;
7.   int buttonY = 100;
8.   int buttonW = 70;
9.   int buttonH = 20;
10. 
    
11.   buttonX = 80*nr + 10;
12.   rect (buttonX, buttonY, buttonW, buttonH);
13.   text (text, buttonX, buttonY);
14. } //  func button
    
15. 
    
16. void draw () {
17.   button(1, "Button1");
18.   button(2, "Button2");
19.   button(3, "Button3");
20.   button(4, "Button4");
21.   button(5, "Button5");
22.   button(6, "Button6");
23. }

In the original code: