S obzirom na to da moj brat ne voli meso svaki dan, danas neće biti kobasica ni slanine.

Yes. S obzirom na to da is a fixed expression meaning considering that, given that, or sometimes since in the sense of giving a reason.

It is best learned as one chunk. Literally, it is built from words meaning something like with regard to the fact that, but learners usually do not need to analyze it word by word every time.

It is a bit more formal or careful in tone than jer.

Usually, yes.

A simpler version would be:

Jer moj brat ne voli meso svaki dan, danas neće biti kobasica ni slanine.

Or, more naturally:

Danas neće biti kobasica ni slanine jer moj brat ne voli meso svaki dan.

The difference is mostly style:

• jer = simpler, more direct, very common
• s obzirom na to da = more formal, explanatory, or written-sounding

You may also hear s obzirom da in speech, but s obzirom na to da is the safer standard form for learners.

Croatian does not use a separate helping verb like English do/does for negation.

So:

• voli = likes
• ne voli = does not like / doesn't like

The negative particle ne goes directly before the verb.

This is very normal in Croatian:

• ne znam = I don't know
• ne mogu = I can't
• ne voli = he doesn't like

Because meso is normally used as a mass noun, just like meat in English.

So ne voli meso means he doesn't like meat in general, not one specific piece of meat.

Croatian often uses singular mass nouns for foods and substances:

• meso = meat
• kruh = bread
• mlijeko = milk
• voda = water

If you wanted to talk about different kinds of meat, then other wording could be used, but in this sentence meso as singular is exactly what you would expect.

Because Croatian often uses the accusative case without a preposition for time expressions meaning frequency, duration, or repeated time.

So:

• svaki dan = every day
• svaku večer = every evening
• svaki tjedan = every week

In this sentence, svaki dan means every day.

A useful detail: dan is masculine inanimate, so its accusative singular looks the same as the nominative. That is why the form stays dan.

It literally means something like today there will not be.

Here biti is being used in an impersonal, existential way, like English there is / there will be.

So:

• danas neće biti kobasica = there won’t be sausages today
• sutra će biti juhe = there will be soup tomorrow

This is a very common Croatian pattern for talking about what is available, present, served, or happening.

Because with existential biti in a sentence like this, especially under negation, Croatian very often uses the genitive.

So the nouns after neće biti are in genitive forms:

• kobasica = genitive plural of kobasica
• slanine = genitive singular of slanina

This is one of the trickier parts for English speakers, because kobasica looks exactly like nominative singular. But here it does not mean one sausage. In this sentence it is genitive plural, so it means sausages.

Why the difference?

• kobasica is a countable noun, so plural makes sense
• slanina is usually treated as a mass noun, so singular makes sense

So the sentence is effectively saying:

• no sausages
• no bacon

Because ni is the normal connector used with negation.

After a negative verb, Croatian often uses ni where English would use or, nor, or and no, depending on context.

Examples:

• Ne voli čaj ni kavu. = He doesn't like tea or coffee.
• Nema kruha ni mlijeka. = There is no bread or milk.
• Neće biti kobasica ni slanine. = There will be no sausages or bacon.

So ni is the expected choice here.

It is singular here: genitive singular of slanina.

That is because slanina is usually treated as a mass noun, like bacon in English. You normally think of it as a food substance rather than as separate countable items.

So:

• slanina = bacon
• slanine = of bacon / any bacon, in the genitive singular here

By contrast, kobasica is countable, so the sentence uses the plural idea: sausages.

Because S obzirom na to da moj brat ne voli meso svaki dan is a subordinate clause giving the reason or background for the main clause.

The main clause is:

danas neće biti kobasica ni slanine

Croatian uses a comma to separate that kind of subordinate clause from the main clause.

So the structure is:

• reason/background clause
• comma
• main statement

This is normal Croatian punctuation.

Yes. Croatian word order is quite flexible.

The original sentence puts the reason first and the result second:

• S obzirom na to da moj brat ne voli meso svaki dan, danas neće biti kobasica ni slanine.

You could also put the main idea first:

• Danas neće biti kobasica ni slanine jer moj brat ne voli meso svaki dan.

That sounds a bit more direct and conversational.

The original version sounds slightly more formal and organized, but both are natural.