This is the 8958th most frequent Polish word.
składając
"Składając" means "while folding" or "submitting," depending on context.
In this sentence, "składając" is a gerund form of "składać" used to indicate the action of submitting happening as a context for another activity.
Składając wniosek, pamiętaj o dołączeniu wszystkich wymaganych dokumentów.
While submitting the application, remember to include all required documents.
Here, "składając" functions as a gerund to describe the manner in which Marek greeted the guests by performing another action—the act of giving wishes.
Marek witał gości, składając im serdeczne życzenia.
Marek greeted the guests by giving them heartfelt wishes.
In this case, "składając" is utilized as a gerund to denote the act of assembling that occurred concurrently with noticing the absence of an element.