Adverbs, as the name would suggest, add to the verb in a sentence.
Many people incorrectly use the adjective ‘real’ — which can mean genuine — when they should use the adverb ‘really’.
The sentence ‘I feel real good.’ should read ‘I feel really well.’ The adverb, ‘really’, adds emphasis to the verb, ‘feel’.
‘He is a real good player.’ becomes ‘He is a really good player.’
In this instance the adverb, ‘really’, adds to the verb, ‘is’.
Many adverbs end in ‘-ly’ e.g., The bird flew swiftly. She ran quickly (not ‘quick’). He boxed cleverly (not ‘clever’). The runner finished the race strongly (not ‘strong’). The aeroplane landed safely (not ‘safe’).