This is the 490th most frequent Czech word.
bohužel
"Unfortunately."
Here, "bohužel" is used at the beginning of the sentence to express regret about an unfavorable situation.
Bohužel jsem zapomněl klíče doma.
Unfortunately, I forgot my keys at home.
In this case, "bohužel" indicates an undesired obligation or constraint causing regret in the situation.
Nemůžu jít s vámi na výlet, bohužel mám práci.
I can't go on the trip with you, unfortunately, I have work.
Here, "bohužel" conveys a sentiment of regret for the unsuccessful attempt at finding something.