"Fortunately" is an adverb that means "by good luck" or "happening in a way that brings good results."
Here are some examples of how to use it in a sentence:
* "Fortunately, I had my umbrella with me when it started to rain." (It means the rain was unexpected but the speaker was prepared because they had an umbrella.)
* "The surgery was a success, and fortunately, there were no complications." (This sentence indicates that the surgery could have had complications, but it did not.)
* "I was late for the meeting, but fortunately, my boss was running a few minutes behind as well." (The speaker was late but managed to avoid getting in trouble.)
As you can see, "fortunately" is used to express relief or gratitude for a positive outcome, often implying that things could have been worse.