This is the 477th most frequent Danish word.
sikkert
Certainly; surely; probably.
Here, 'sikkert' is an adverb indicating the manner in which the action is performed: safely.
Han kører sikkert til arbejde hver dag.
He safely drives to work every day.
In this case, 'sikkert' is used as an adjective meaning 'certain' or 'sure.'
Det er sikkert, at han kommer i morgen.
It is certain that he will come tomorrow.
Here, 'sikkert' functions as an adverb meaning 'probably,' indicating a level of certainty regarding the statement.