Knife is rusting after using it only twice
A list of methods for removing rust from knives can be found at Knife Depot.  In your case, as the rust appears very light and is recent, simply wiping with a vinegar cloth may be sufficient (possibly also needing a wipe with fine steel wool) and then wipe off any remaining vinegar.

In future, it is imperative that you dry the washed knife immediately and then apply a very thin coating of food safe (e.g., vegetable) oil (or fat) - wipe on then wipe off.  Also, don't leave the knife wet (e.g., while using it) for any length of time - wipe with a dry cloth.