Both forms are correct.
Due to standardizing and simplifying American English spelling, which started with Noah Webster dictionary in 1828, traveling is widely used in US. Correct British spelling is still travelling, with double l, according to the rule of doubling the last consonant of consonant-vowel-consonant combination at the end of the word, whenever we add a suffix to it. Therefore both forms are correct, whereby travelling is accepted as British English spelling and traveling is considered correct in American English.

Correct spelling

travelling

Correct spelling, explanation: preferred in British English.

Correct spelling

traveling

Correct spelling, explanation: preferred in American English.


Definition of travelling/traveling:
verb, gerund form of travel, to journey, to move from one place to another
I love travelling by train, it is so relaxing!
I’m traveling to Florida next month.