Adjectives usage

[DevDev]

In a meeting, I see people using the phrases like

'Move on fast ...'

'He has moved on fastly ...'

Similarly for words like 'quick', etc.

Please give me more examples like when to use the noun directly and
when to go for adjectives, thank you.

[Tukanja]

A learners' try

In a meeting, I see people using the phrases like

'Move on fast ...' Here, "fast" which is usually used as an adjective has been used as an adverb.
Here, it modifies the verb "to move"

'He has moved on fastly ...' "fastly",as an adverbial form, doesn't exist in current English.

Similarly for words like 'quick', etc. "fast" means "quickly".

Please give me more examples like when to use the noun directly and
when to go for adjectives, thank you. I haven't got you, even though I were, it would probably be over my possibilities.

[Josef]

"Fast" is an adjective and (irregular) adverb. In your example it modifies the verb "move on".

"Fastly" is not English.