Quickly; speedily; rapidly.
23yrold3yrold is a name that is difficult to type fastly.
An archaic word for "fast," which is not used anymore.
The adverb of "fast" is "fast." Fastly is wrong.
Fastly means to go fast and quickly.
An example would be "STEPHANIE, ARE YOU DRAWING YOUR CARROT FASTLY?". Technically, fastly is not a correct/real word, it is more grammatically correct if you say "STEPHANIE, ARE YOU DRAWING YOUR CARROT FAST."