This is the 4067th most frequent Russian word.
несомненно
Undoubtedly.
Here, 'несомненно' is used at the beginning of the sentence to express a definitive opinion about the movie's value.
Несомненно, этот фильм стоит посмотреть.
Undoubtedly, this movie is worth watching.
In this sentence, 'несомненно' acts as an adverb emphasizing the speaker's certainty about her qualities.
Она несомненно талантлива и трудолюбива.
She is undoubtedly talented and hardworking.
Here, 'несомненно' emphasizes that the improvement in results is certain and clear due to the training.