Children who were playing in the park laughed joyfully. Here 'joyfully' is a/an -

• Adverb
- যেসব word noun বা pronoun ব্যতীত অন্য যেকোনো parts of speech, বিশেষ করে verb কে modify করে সেগুলোকে Adverb বলে।
- এখানে 'joyfully' শব্দটি verb, laughed কে modify করছে বিধায় এটি Adverb/ Adverb of Manner.

• 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, বাচ্চারা কিভাবে হাসছে এটা বর্নিত হয়েছে, তাই এটি হচ্ছে Adverb of Manner.