This is the 13918th most frequent German word.
flirtende
"Flirtende" in German means "flirting" or "flirtatious."
Here 'flirtende' is used as an adjective modifying 'Kellnerin' to describe her behavior.
Die flirtende Kellnerin hat ihm ein Getränk empfohlen.
The flirtatious waitress recommended a drink to him.
In this case, 'flirtenden' is in plural form, describing the behavior of 'Gäste'.
Er beobachtete die flirtenden Gäste am anderen Tisch.
He observed the flirtatious guests at the other table.
Here 'flirtenden' is used to modify 'Stimme', indicating the tone or nature of the voice.