Incorrect spelling


Incorrect spelling, explanation: this form is the wrong one because suffix -ly is added to the full form of an adjective, so beautiful will become beautifully – with double l. This is why beaufituly is incorrect.

Correct spelling


Correct spelling, explanation: to create an adverb from an adjective a suffix -ly is added to the word, for example quickquickly. The same rule applies to the word beautiful, which ends with the consonant l. Beautiful + ly is beautifully (l doubles, because it is at the end of the adjective and there is another l in the suffix). So, beautifully is the correct form and beautifuly is an incorrect one.

Definition of beautifully:
adverb, in a nice, beautiful way
For my birthday I got a beautifully painted picture.
The dress was beautifully hand-made.