At least two different meanings:
on that night
nightly, every night
for the evening
Maganda ang gabi.
The night is beautiful.
Kulay dugo ang gabi.
The night is the color of blood.
Ang gabing ating pinakahihintay.
The night we’ve been waiting for the most.
There’s no equivalent phrase for bidding someone ‘good night’ in Tagalog.