He swimswell. The underlined word refers to -

Adverb of manner:
- An adverb of manner is an adverb (such as quickly or slowly) that describes how and in what way an action, denoted by a verb, is carried out.
- These adverbs are also called manner adverbs or manner adverbials. i.e. They dress elegantly. 

- প্রদত্ত প্রশ্নে, বলা হচ্ছে, সে ভালো সাঁতার কাটে। এখানে সে কেমন সাঁতার কাটে এটা বর্ণিত হচ্ছে। 
- সুতরাং সঠিক উত্তর হবে  Adverb of Manner. 

Source: Cambridge Dictionary