わたしたちは寝るとき「おやすみなさい」といいます。

When we go to bed, we say "good night".

わたしたちは寝(ね)るとき「おやすみなさい」といいます。

Watashitachi wa neru toki" oyasuminasai" to iimasu.

私たち (わたしたち、わたくしたち)

we; us

は (は)

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

寝る (ねる)

to lie down; to go to bed; to lie in bed; to sleep (lying down); to sleep (with someone, i.e. have intercourse); to lie idle

とき (とき)

regular (stops at every station) Jouetsu-line Shinkansen

お休みなさい (おやすみなさい)

good night

と (と)

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)

結う (ゆう、いう)

to do up (hair); to braid; to fasten; to fix

Readings: シン、ね.る、ね.かす、い.ぬ、みたまや、や.める

Meanings: lie down, sleep, rest, bed, remain unsold