蚊が翼を上下に叩くと、独特のブンブン音が出ます。

Meaning: when mosquitoes beat their wings up and down, they produce a distinctive buzzing sound

蚊: mosquito
が: is, there, but, ga, will, however
翼: wing, wings, winged, blade, feather, ala
を: o, the, to, wo
上下: up and down, high and low, high and low, upper and the lower parts, unloading and loading, praising and blaming, samurai garb, going up and down, top and bottom, government and the people, up-and-down, vertical, upside down
に: in, to, on, at, into, upon
叩く: hit, slap, beat, to hit, knock, clap, attack, strike
と: and, with, if
独特: unique, distinctive, special, peculiar, characteristic, uniqueness, peculiarity, inimitable
の: to, of
ブンブン: buzz, buzzing, whirring, humming, hum
音: sound, noise, tone, note
が: is, there, but, ga, will, however
出: out, go out, come out, exit, emit
ます: will, to be, i will, to make, to do, to have