int i=0;
for(int i=0;i<5;i++){
    //code goes here
}

Loop has 3 parts
initialization
condition
increement

flow goes this way
initialization, checks the condition(above loop will check for i, If i is less than 5), increement and run the loop statement

initialized with 0, check the condition(if i is still less than 5), increement i++(i=1), run the loop statement
check the condition (if i is still less than 5), increement i++(i=2), run the loop statement
check the condition (if i is still less than 5), increement i++(i=3), run the loop statement
check the condition (if i is still less than 5), increement i++(i=4), run the loop statement
check the condition (if i is still less than 5), increement i++(i=5), run the loop statement
check the condition (if i is still less than 5)- No value of i has become 5 now, so looping process is finised

And now, i(loop variable) is outside of the valid range of the condition, i.e value of i is not less than 5 now, it has become 5


Hope it solves your query, Questions are always welcome.

Cheers
Happy Coding!!!!