Exegesis:

tines hoi logoi houtoi hous antiballete pros allēlous ‘what are these words which you cast at each other?’

antiballō lit. ‘to cast against,’ here of words, hence ‘to exchange.’

peripatountes ‘walking,’ hence ‘as you walk along.’

kai estathēsan “they came to a halt” (The Four Gospels – a New Translation), ‘they stood still,’ ingressive aorist.

skuthrōpoi ‘gloomy,’ ‘downcast.’

Translation:

What is this conversation which you are holding with each other, or simply, ‘what affair are you talking about’ (Ekari), ‘what are you discussing’ (cf. An American Translation).

Looking sad, or, “with sad faces” (Good News Translation), ‘(their) faces clouded’ (Ekari). For sad see references on 18.23.

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.