The word fast can be a noun meaning abstinence from food.
It is also a verb with the same meaning, to refrain from eating (as for religious or for medical purposes).
It is often an adjective meaning quick or rapid, or tightly attached (fastened).
It is also an adverb meaning quickly and rapidly, or tightly as above.
grammer
"Fast" is an adjective, because it describes a noun (e.g., a fast car).
Fasted is a verb
adverb
Fasted is a verb
Went by fast.
simile
Runs is a verb (3rd person singular), and fast is an adverb.
"Fast-paced" is an adjective. It describes something that is moving or happening quickly.
Similes
In the sentence "Ram walks fast," the word "fast" is an adverb modifying the verb "walks." It describes how Ram walks.
Face, Arm, Speech, Time