Questions & Answers about בלילה היה לי חלום ארוך על בית ליד הים.
בלילה means at night or during the night.
It is made from the preposition ב־ (in / at) plus הלילה (the night), which contract into one written word in Hebrew: בלילה.
So literally, it is something like in the night, even though in natural English we usually say at night.
A native English speaker may expect two words, but in Hebrew this kind of combination is very common.
Hebrew often puts a time expression at the beginning of a sentence, especially to set the scene.
So:
בלילה היה לי חלום ארוך...
= At night, I had a long dream...
This sounds very natural in Hebrew. Hebrew word order is more flexible than English, so starting with the time phrase is normal and often stylistically smooth.