Subsolul este gol.

Because -ul is the Romanian definite article attached to the end of a masculine/neuter singular noun.

• subsol = a basement / basement
• subsolul = the basement

Romanian usually puts the at the end of the noun instead of using a separate word like English does.

Subsol is a neuter noun in Romanian.

Romanian neuter nouns behave:

• like masculine in the singular
• like feminine in the plural

So in the singular, subsolul takes:

• the masculine/neuter singular definite ending -ul
• the masculine singular adjective form gol

That is why you get Subsolul este gol, not goală or goale.

Because adjectives in Romanian must agree with the noun in gender and number.

Here, subsolul is:

• singular
• neuter, which acts like masculine in the singular

So the correct adjective form is gol.

Compare:

• subsolul este gol = masculine/neuter singular
• camera este goală = feminine singular
• subsolurile sunt goale = plural

Este is the 3rd person singular form of a fi (to be).

So:

• eu sunt = I am
• tu ești = you are
• el/ea este = he/she/it is

In Subsolul este gol, este links the subject and the adjective, just like is in English:

• The basement is empty.

Romanian normally uses the verb here; you do not usually leave it out in standard sentences.

Yes. E is a very common short form of este.

So both are correct:

• Subsolul este gol — a little more formal or careful
• Subsolul e gol — very common in everyday speech

Both mean the same thing.

The normal, neutral order is:

• Subsolul este gol.

Romanian word order is fairly flexible, but changing it usually adds emphasis or sounds more literary.

For example:

• Gol este subsolul. — unusual, emphatic, poetic, or contrastive

For most learners, the standard pattern subject + verb + adjective is the safest choice.

Romanian usually uses an enclitic definite article, which means the article is attached to the end of the noun.

So instead of:

• the basement

Romanian says:

• subsolul

This is one of the big structural differences between English and Romanian.

A simple English-friendly approximation is:

• soob-SOL-ool

And the whole sentence can be approximated as:

• soob-SOL-ool YES-te gol

A few notes:

• u is usually pronounced like oo in food
• o is a clear o sound
• gol sounds roughly like gol with a short, clear o, not like English goal

Not only. Gol can mean several related things depending on context, such as:

• empty
• bare
• vacant
• hollow in some contexts

In Subsolul este gol, the most natural meaning is empty.

So the adjective is broad, and context tells you which English word fits best.

Usually, yes, but there can be small context differences.

• subsol = basement, especially the underground level of a building
• pivniță often means cellar, especially for storage, wine, food, etc.

So if you mean the lower underground level of a building in general, subsol is the natural word.

The plural is:

• Subsolurile sunt goale. = The basements are empty.

Notice the changes:

• subsolul → subsolurile
• este → sunt
• gol → goale

This shows both noun and adjective agreement in the plural.