Assert Type defines how submitting a form affects the result of test (passes or fails)
if you choosed option 1 in your test step, then during execution test will pass only if your form is submitted without any errors it will fail in all other conditions
if you choosed option 2 in your test step then, during execution test will pass only if your form submission is cancelled
if you choosed option 3 in your test step then, during execution test will pass for both for failed form submission / succesful form submission.
assert type informs test runner - the condition in which test should pass or faill
-satheesh
