How for loop work ? I am really confused with it.

Answer 1

For loop should be used when you know how many times you want to repeat some code.
There's a simple example:
for (i=0; i<5; i++)
{
some code
}
1. i=0 --> you start with index 0
2. i<5 --> check if your index is less than 5 (0<5 is true so you continue)
3. do some code inside loop
4. i++ --> add 1 to your i index, so it's 0+1=1
5. i=1 --> index is 1
6. check if index is less than 5 (1<5 so you continue)
7. .... etc
Loop ends when your condition (i<5) isn't true. So when i=5, 5<5 is false and you quit loop.

Answer 2

for(int i=0; i<10; i++){
Do something here 10 times
}

basically is says a variable named i equals 0. you want to run the loop until the variable i is no longer less than 10. each time it runs you want to add 1 to the variable I.