Soldul este mare.

Because Romanian usually puts the definite article at the end of the noun.

• sold = balance / a balance
• soldul = the balance

So in Soldul este mare, the speaker is talking about a specific balance: the balance.

This is a very common Romanian pattern:

• băiat = boy
• băiatul = the boy
• cont = account
• contul = the account

In this sentence, sold usually means balance, especially in a financial context, such as a bank account balance.

So soldul most naturally means the balance.

Depending on context, Romanian words can sometimes have more than one use, but for learners, the safest understanding here is:

• sold = balance
• soldul = the balance

Este is the 3rd person singular form of the verb a fi, which means to be.

So:

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

In Soldul este mare, este means is.

A very common shorter spoken form is e:

• Soldul este mare.
• Soldul e mare.

Both mean the same thing.
Este sounds a bit fuller or more careful; e is very common in everyday speech.

Because mare is a predicate adjective here. It describes the subject soldul through the verb este.

This is similar to English:

• The balance is large.
• subject + is
  • adjective

Romanian works the same way here:

• Soldul
  • este
    • mare

So mare is not directly attached to the noun as in the large balance. It comes after este because it is part of the statement about the subject.

Mare usually means big or large.

In this sentence, large is the most natural English translation, because balance is usually described as large rather than big in standard English.

A few examples:

• o casă mare = a big house
• un oraș mare = a large/big city
• soldul este mare = the balance is large

So the word itself is broad, but English may choose different translations depending on context.

In the singular, mare stays the same for both masculine and feminine nouns.

For example:

• băiatul este mare = the boy is big
• casa este mare = the house is big

In the plural, it changes to mari:

• băieții sunt mari = the boys are big
• casele sunt mari = the houses are big

So in this sentence, mare is singular because soldul is singular.

Sold is a neuter noun in Romanian.

Romanian neuter nouns behave like:

• masculine in the singular
• feminine in the plural

That is why the singular looks like this:

• un sold
• soldul
• sold mare

And the plural looks like this:

• două solduri
• soldurile
• solduri mari

This is a very important Romanian pattern.

Because Romanian usually expresses the by attaching it to the noun, instead of putting it in front.

Compare:

• English: the balance
• Romanian: soldul

This is one of the biggest differences from English.
It is called the enclitic definite article.

More examples:

• omul = the man
• fata = the girl
• contul = the account

So soldul already includes the meaning of the.

The normal, neutral order is:

• Soldul este mare.

Romanian can sometimes change word order for emphasis, but that would sound marked or literary in many cases.

For a learner, the standard pattern to use is:

• subject + verb + adjective

So Soldul este mare is the safest and most natural version.

A simple learner-friendly pronunciation guide would be:

SOHL-dool YES-teh MAH-reh

A few notes:

• o is usually like o in more (without the English glide)
• u is like oo in food
• e is like e in met
• r is rolled or tapped, not the English r

Word stress:

• SOL-dul
• ES-te
• MA-re

Yes. That is very common and natural.

• Soldul este mare. = more full/formal/neutral
• Soldul e mare. = very common in everyday speech

Both are correct.
As a learner, it is good to recognize both forms.

Not really in normal usage.

• soldul este mare = the balance is large
• marele sold would mean something like the large balance, with the adjective placed before the noun in a more marked or literary style

In ordinary Romanian, if you want the large balance, the usual form is:

• soldul mare

But that is a noun phrase, not a full sentence.

So:

• soldul este mare = full sentence
• soldul mare = noun phrase, the large balance

Because the sentence is about a specific balance, not an unspecified one.

• soldul = the balance
• un sold = a balance

So Romanian is not missing a/an here. It simply is not needed, because the noun is definite.

Compare:

• Un sold este mare. = A balance is large.
  This is grammatically possible, but much less natural in most contexts.
• Soldul este mare. = The balance is large.
  This is the normal kind of sentence when talking about a particular balance.

Yes, absolutely.

It has everything needed:

• Soldul = the subject
• este = the verb
• mare = the adjective describing the subject

So it is a complete and normal Romanian sentence.