Obviamente, tenemos un problema.

Because problema is a masculine noun in Spanish: el problema, un problema.

Some nouns ending in -a are masculine, especially many words of Greek origin, such as:

• el problema
• el sistema
• el tema
• el clima

So in this sentence, un problema is completely normal.

Tenemos means we have, while hay means there is / there are.

So:

• Tenemos un problema = We have a problem
• Hay un problema = There is a problem

Both are possible in Spanish, but they are not exactly the same.

• Tenemos un problema sounds more direct and involved: this is our problem / we are dealing with it
• Hay un problema is more neutral: a problem exists

Spanish often leaves out subject pronouns when they are clear from the verb form.

• tenemos already means we have
• so nosotros tenemos un problema is possible, but usually unnecessary

Spanish speakers normally say:

• Tenemos un problema

They may add nosotros only for emphasis, contrast, or clarity.

Tenemos is the present tense of the verb tener (to have), specifically the first person plural:

• yo tengo = I have
• tú tienes = you have
• él/ella tiene = he/she has
• nosotros tenemos = we have
• vosotros tenéis = you all have
• ellos tienen = they have

So tenemos means we have.

Here, obviamente is being used as a sentence adverb: it comments on the whole statement, like obviously in English.

So the comma helps separate it from the rest of the sentence:

• Obviamente, tenemos un problema.

This is very natural in writing.

Without the comma, Obviamente tenemos un problema, it may still be understood, but the comma is preferred when obviamente introduces the speaker’s attitude toward the whole sentence.

Yes. Spanish allows some flexibility.

Common possibilities include:

• Obviamente, tenemos un problema.
• Tenemos, obviamente, un problema.
• Tenemos un problema, obviamente.

All of these can work, but they may sound slightly different in rhythm or emphasis.

The version at the beginning is very common when the speaker wants to frame the whole statement as obvious.

A rough pronunciation is:

• ob-bya-men-te

More carefully in standard Spanish:

• obvia sounds roughly like OB-bya
• mente sounds like MEN-te

A few useful notes:

• v and b are pronounced very similarly in Spanish
• the stress is on -men-: obviaMENte
• in Spain, the t is a clear dental t, not like the softer English t in some accents

Usually yes, but you should be a little careful.

In many cases, obviamente works just like obviously:

• Obviamente, tenemos un problema. = Obviously, we have a problem.

But as in English, it can sound:

• neutral and logical
• emphatic
• sarcastic, depending on tone

So the meaning is similar, but the tone depends a lot on context and intonation.

Yes, both are possible, but the tone changes slightly.

• obviamente = obviously
• evidentemente = evidently / clearly / obviously, often a bit more formal
• claramente = clearly

Examples:

• Obviamente, tenemos un problema.
• Evidentemente, tenemos un problema.
• Claramente, tenemos un problema.

For everyday speech, obviamente is very natural.

In Spanish, singular countable nouns usually need an article or another determiner.

So Spanish normally says:

• Tenemos un problema = We have a problem

Saying just Tenemos problema would usually sound incomplete or non-standard in most contexts.

The article un works like English a.

It is neutral. It can fit both informal and fairly formal situations.

• In conversation, it sounds normal and natural.
• In a serious discussion, it still works.

The form itself is not especially casual or especially formal. The tone mostly depends on how it is said.

Yes, absolutely. Obviamente, tenemos un problema is a natural sentence in Spain.

That said, in real conversation, Spanish speakers might also choose alternatives depending on tone, such as:

• Está claro que tenemos un problema.
• Tenemos un problema, está claro.
• Pues sí, tenemos un problema.

But your original sentence is completely correct and idiomatic.

The structure is:

• Obviamente = adverb
• tenemos = verb
• un problema = direct object

So the core sentence is:

• Tenemos un problema = We have a problem

And obviamente adds the idea obviously to the whole statement.

Yes. Just like English Obviously, we have a problem, it can be either sincere or sarcastic depending on intonation and context.

For example:

• calm, serious tone: a genuine statement
• annoyed tone: sarcastic or frustrated
• exaggerated tone: very sarcastic

So the grammar stays the same, but the delivery changes the meaning a lot.