Exegesis:

estōsan humōn hai osphues periezōsmenai ‘your waists must be girded,’ i.e. ‘you must be prepared for action.’ estōsan is imperative 3rd person plural. humōn is emphatic and indicates implicitly the agents of the girding.

osphus ‘waist,’ ‘loins’ as the place where a belt or girdle is worn.

perizōnnumi ‘to gird about,’ i.e. to tuck up one’s long garment by pulling it through a belt, here in the passive, with the part of the body where the belt is worn as subject.

kai hoi luchnoi kaiomenoi ‘and your lamps (must be) burning,’ with estosan understood, implying that it is night and anticipating the events told in vv. 36f. For luchnos cf. on 8.16. kaiō also 24.32.

Translation:

Let your loins be girded. A rather literal rendering sometimes conveys the required meaning, e.g. ‘tighten your belt’ (Ekari), ‘tighten the belt about your loins’ (Kele). Elsewhere the term for a similar act has the same metaphorical meaning, e.g. ‘have (it)-tucked-in’ (Balinese), ‘have (it)-rolled-up’ (Toraja-Sa’dan, similarly Yao), ‘have your clothing tucked up’ (Shona 1966), i.e. make ready for work at hand, by pulling up the long skirt-like garment between the legs and tucking it into the belt at the back, or by rolling or pulling it up around the waist. But in several languages only a non-figurative, functional rendering is acceptable, e.g. ‘be ready always’ (Tzeltal), ‘be prepared’ (Dan), ‘prepare yourselves,’ or a combination of a functional rendering of this (and the next) phrase with a literal one, e.g. “be ready for action, with belts fastened and lamps alight” (New English Bible, cf. also Good News Translation, The Four Gospels – a New Translation).

Your lamps burning, or, ‘and let your lamps give light,’ ‘keep/have your lamps shining.’ A non-figurative rendering of this phrase is both undesirable and unnecessary because of the short parable in vv. 36ff. For lamp see 8.16; the rendering chosen may also influence that of the verb, e.g. if the language distinguishes between the burning or light of a lamp and of a torch.

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.