A franquia é muito alta.

Here, a is the definite article meaning the. It matches franquia, which is a feminine singular noun.

So:

• a franquia = the deductible / the franchise / the allowance, depending on context

It is not the preposition a meaning to in this sentence.

Because franquia is a grammatically feminine noun in Portuguese. In Portuguese, nouns have grammatical gender, and other words often have to agree with that gender.

That is why you get:

• a franquia
• alta

A very useful habit is to learn nouns together with their article:

• a franquia, not just franquia

É comes from ser, and está comes from estar.

In this sentence, é usually sounds more natural if you are describing the fee/deductible/allowance as a general characteristic:

• A franquia é muito alta. = it is high, as a general fact

If you said A franquia está muito alta, that would usually sound more like:

• it is high right now
• it has become high
• you are commenting on its current state

So both can be possible in some contexts, but é is the safer, more neutral choice here.

Because adjectives in Portuguese usually agree with the noun they describe.

Since franquia is feminine singular, the adjective also has to be feminine singular:

• masculine singular: alto
• feminine singular: alta
• masculine plural: altos
• feminine plural: altas

So:

• o valor é alto
• a franquia é alta

Here, muito means very.

In this sentence, it is an adverb, modifying the adjective alta:

• muito alta = very high

When muito is an adverb, it does not change form.

Compare:

• A franquia é muito alta. → muito = very
• Há muita burocracia. → muita = a lot of, agreeing with a feminine noun

So in your sentence, muito stays muito.

It can mean either, depending on the noun.

With things like prices, fees, rates, temperatures, and deductibles, alto/alta usually means high:

• preço alto = high price
• taxa alta = high rate
• franquia alta = high deductible / high franchise fee / high allowance threshold, depending on context

With people or buildings, it can mean tall:

• um homem alto = a tall man

So here, alta means high, not tall.

Because Portuguese, like English, normally uses high rather than big for things like prices, rates, fees, and deductibles.

So:

• preço alto = high price
• juros altos = high interest
• franquia alta = high deductible / high fee

If you used grande, it would sound less natural here, because grande usually means big/large in size, importance, or extent, not high in this kind of financial sense.

Yes. This is a very normal Portuguese sentence pattern:

• A franquia = subject
• é = verb
• muito alta = description after the verb

The adjective comes after ser because it is part of the predicate:

• A casa é grande.
• O carro é caro.
• A franquia é muito alta.

This is completely standard.

It can refer to different things depending on context. Common meanings include:

• a franchise
• an insurance deductible
• an allowance or usage limit, such as a baggage or data allowance

The grammar of the sentence stays the same no matter which meaning is intended.

The accent is important because é and e are different words:

• é = is
• e = and

So the accent helps distinguish them in writing.

It also marks the stressed vowel in é.

A good approximation is:

• fran-KEE-a

A few pronunciation notes:

• the stress falls on qui
• qu before i sounds like k
• the u in qui is not pronounced separately
• the first syllable has a nasal sound: fran

So a rough English-friendly version is fran-KEE-ah.