for i in {1..10}; do echo "$i"; done
In Bash, {1..3} is expanded to the numbers 1 2 3. You can read more about it in man bash, search for "Brace Expansion".
By using an expression like this in a for loop, we can do something for each number in the range. In this example we simply print the number using echo.
This is Bash specific, it may not work with simply /bin/sh.
for ((i=1; i<=10; ++i)); do echo $i; done
printf '%s\n' {1..10}