This is the 11516th most frequent Polish word.
językiem
"Językiem" is the instrumental case of "język," meaning "language" or "tongue" in English.
In this sentence, 'językiem' is the instrumental singular form of 'język', meaning 'tongue', used to indicate a physical action done with 'using the tongue'.
Obca dziewczyna dotknęła lodu swoim językiem.
A strange girl touched the ice with her tongue.
Here, 'językiem' again is the singular instrumental form of 'język', signifying the instrument used for the action—'the dog is licking with its tongue'.
Twój pies oblizuje się językiem.
Your dog licks itself with its tongue.
Here, 'językami' is the instrumental plural form of the noun 'język', meaning 'languages', used to describe the means by which something is done, i.e., speaking languages.