This is the 14582nd most frequent German word.
lächelnden
"Lächelnden" means "smiling" (as a participle or adjective).
Used as an adjective associated with the noun 'Ausstrahlung', describing its quality as 'smiling'.
Das Mädchen mit der lächelnden Ausstrahlung betrat den Raum.
The girl with the smiling aura entered the room.
Here, it is used as an adjective modifying 'Freunde', highlighting that the friends were smiling.
Er erinnerte sich an seine lächelnden Freunde auf dem Foto.
He remembered his smiling friends in the photo.
Although metaphorically, 'lächelnden' acts as an adjective attributing the quality of 'smiling' to 'Blumen'.