Tensiunea este prea mare.

Because -a at the end is the definite article in Romanian.

• tensiune = tension / a tension
• tensiunea = the tension

Romanian usually puts the definite article at the end of the noun, unlike English, which uses a separate word (the).

So:

• tensiunea = the tension
• fata = the girl
• cartea = the book

Este means is.

It is the 3rd person singular form of the verb a fi = to be.

So:

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

In everyday speech, Romanians often use the shorter form e instead of este:

• Tensiunea e prea mare.

This means exactly the same thing.

No—prea usually means too, not very.

So:

• prea mare = too big / too high
• foarte mare = very big / very high

That is an important difference:

• Tensiunea este foarte mare. = The tension/pressure is very high.
• Tensiunea este prea mare. = The tension/pressure is too high.

So prea often suggests more than is acceptable or desirable.

Mare means big / large / high, depending on context.

It matches tensiunea, which is a feminine singular noun. However, mare is one of those adjectives whose singular masculine and feminine forms are the same:

• un om mare = a big man
• o casă mare = a big house

But in the plural it changes:

• mari = big / large

Example:

• Tensiunile sunt prea mari. = The tensions/pressures are too high.

Romanian often uses mare where English uses high, especially with things like:

• price
• temperature
• pressure
• blood pressure
• voltage
• level/intensity

So mare can mean more than just physical big. In this sentence, it naturally translates as high rather than big.

It can mean different things depending on context, for example:

• tension
• pressure
• blood pressure
• voltage

So Tensiunea este prea mare could mean different things in different situations:

• in medicine: The blood pressure is too high
• in electronics: The voltage is too high
• in a general situation: The tension is too high

Romanian often relies on context to make this clear.

This is the normal, neutral word order:

• subject + verb + adverb + adjective

So:

• Tensiunea = subject
• este = verb
• prea mare = predicate adjective phrase

You can change the order for emphasis, but the standard version is:

• Tensiunea este prea mare.

A more marked version like Prea mare este tensiunea would sound unusual in normal conversation and would only be used for special emphasis or style.

Normally, in standard Romanian, no—you keep the verb to be.

So the normal sentence is:

• Tensiunea este prea mare.
• or more conversationally: Tensiunea e prea mare.

Unlike some languages, Romanian does not usually drop the present tense of to be in ordinary statements.

A simple English-friendly pronunciation guide would be:

ten-see-OO-neh-a YES-teh PREH-a MAH-reh

A few notes:

• si in tensiunea sounds like see
• ea at the end of tensiunea is pronounced as two vowels together
• prea is one syllable or very close to one smooth unit for many speakers
• r in Romanian is usually trilled or tapped, not the English r

A rougher, more natural flow is:

ten-see-OO-nya YES-te PREA MA-re

It is singular.

You can tell because:

• the noun is singular: tensiunea
• the verb is singular: este
• the adjective is singular: mare

The plural would be:

• tensiunile sunt prea mari.
• The tensions/pressures are too high.

Notice the changes:

• tensiunea → tensiunile
• este → sunt
• mare → mari

Because Romanian usually attaches the to the end of the noun as a suffix.

Compare:

• English: the tension
• Romanian: tensiunea

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

Some more examples:

• băiat = boy → băiatul = the boy
• fată = girl → fata = the girl
• carte = book → cartea = the book

So when learning Romanian, it helps to think of the article as part of the noun form.

Yes. That is very common and natural in speech.

• este = more full/formal/neutral
• e = shorter, very common in everyday Romanian

Both mean exactly the same thing:

• Tensiunea este prea mare.
• Tensiunea e prea mare.

It is a predicate adjective phrase.

The structure is:

• Tensiunea = subject
• este = linking verb
• prea mare = predicate adjective

This is similar to English:

• The pressure is too high
• The house is big
• The problem is serious

So mare is not directly describing the noun inside the noun phrase; instead, it comes after este and tells you a quality of the subject.

Normally, no. Romanian usually does not use a subject pronoun unless it is needed for emphasis or contrast.

So the natural sentence is:

• Tensiunea este prea mare.

You would not normally say:

• Ea este prea mare

unless ea clearly refers back to tensiunea and you specifically want emphasis, like It is too high.

Romanian often leaves subject pronouns out because the verb form already helps identify the person and number.