Luke 12:35 Let your loins be girded about, and your lights burning;
They must be: your groins having braced around themselves. And the lamps? Firing themselves up!
This verse is a surprise: starting a new topic in a very sudden way, seemingly without context. This is typical of verses that answer a question where the question was not recorded. Sections like this read like a monologue, but in reading the Greek, they seem more like one side of a conversation. As we commonly see in Luke, this verse contains one unique term and an uncommon one used for the first time by Jesus.
"Let...be" is from the verb "to be" to try and capture and Greek verb form we don't use in English, the third-party command. In English, commands are always in the second person, "Be this!" or "Do this!" The third party command is not spoken to the listener or the object that is the subject but about the subject. In English, it is more like saying "it must be" or "they must be!".
The word translated as "your" is plural addressing a group of Jesus's listeners.
"Loins" is from the Greek word that means "loin", and "lower part of back". This is the only time Jesus uses this word. It is one of the subjects of this sentence.
The Greek verb translated as "gird" means "to gird around ", that is to say, "brace around". It is in the form of an adjective, "bracing around" but in the past-perfect tense, "having braced around" but in a form where the subjects act on themselves "having braced around themselves".
The Greek word translated as "and" is used as the conjunction "and", but it also is used to add emphasis ("also").
The Greek noun translated as "lights" means "lamps" or any form of portable light.
The Greek verb translated as "burning" means "to kindle", "to set on fire", "to burn," and "to bake pottery." Again, it is an adjective so "setting on fire" or "burning", but in the present tense. Again, the subjects act on themselves, "firing themselves up!"
περιεζωσμέναι [uncommon](part pl perf mp fem nom) "Gird" is perizōnnymi, which means "to gird round oneself", and "to gird oneself with".
καὶ (conj/adv) "And" is kai, which is the conjunction joining phrases and clauses, "and," or "but." After words implying sameness, "as" (the same opinion as you). Used in series, joins positive with negative "Not only...but also." Also used to give emphasis, "even", "also," and "just." also."