夜になると、たくさんのホタルが見れるよ。

Meaning
at night you can see lots of fireflies

Vocab used in this sentence

night, evening
in, to, on, at, into, upon
なる
be, get, become, comes, to become
and, with, if
たくさん
lot, a lot, many, much, hearty
to, of
ホタル
fire fly, firefly, lightning bug
is, there, but, ga, will, however
見れる
see, can see, possible to see, viewable
the, yo, ll