A bolsa de sangue está pronta.

• A = the
• bolsa = bag or pouch
• de sangue = of blood / blood
• está = is (from estar)
• pronta = ready

So the structure is literally The bag of blood is ready, even though the natural English meaning may be shown to the learner in a smoother way.

Because bolsa is a feminine noun in Portuguese, so it takes the feminine singular article a.

• a bolsa = the bag
• uma bolsa = a bag

In Portuguese, nouns have grammatical gender, and the article must match the noun.

Portuguese often uses de + noun where English uses a noun as an adjective.

So:

• bolsa de sangue = literally bag of blood
• natural meaning: blood bag

This is very common in Portuguese:

• copo de água = glass of water
• mesa de madeira = wooden table
• banco de dados = database

While an adjective form may exist in some contexts, bolsa de sangue is the normal and natural way to say it here.

Portuguese has two main verbs for to be: ser and estar.

Here, estar is used because pronta describes a current state or condition: the blood bag is now ready.

• está pronta = is ready
• é pronta would sound unnatural here

A helpful rule:

• ser = identity, definition, permanent characteristics
• estar = state, condition, location, temporary situation

Since readiness is a state, estar is the correct choice.

Because pronta agrees with bolsa, which is feminine singular.

Agreement in Portuguese is very important:

• a bolsa está pronta = feminine singular
• o material está pronto = masculine singular
• as bolsas estão prontas = feminine plural
• os materiais estão prontos = masculine plural

So pronta changes to match the noun it describes.

It usually means ready, prepared, or finished/prepared for use, depending on context.

In this sentence, está pronta most naturally means something like:

• is ready
• is prepared
• is ready for use

In a medical setting, it suggests the blood bag has been prepared and is available for the next step.

Because de sangue is being used in a general descriptive sense: it tells you what kind of bag it is.

• bolsa de sangue = blood bag / bag of blood
• bolsa do sangue would mean something more like the blood’s bag or the bag of the blood, which is not the intended meaning

So de + noun without an article often works like an English descriptive noun:

• xícara de chá = cup of tea
• garrafa de vinho = bottle of wine
• bolsa de sangue = blood bag

Yes, you could say Está pronta a bolsa de sangue, but it sounds more marked or stylistically different.

The most neutral and common order is:

• A bolsa de sangue está pronta.

Starting with the verb:

• Está pronta a bolsa de sangue. can sound more formal, literary, or like you are emphasizing the state first.

For everyday learning, the standard word order is the safest choice.

Está has an acute accent to show the stressed syllable.

It is pronounced roughly like es-TAH in Brazilian Portuguese.

The accent helps distinguish pronunciation and stress. Without going too deeply into spelling rules, the key point is:

• está = stress on the last syllable

This is the he/she/it and you form of estar:

• eu estou
• você está
• ela está

A rough pronunciation guide is:

ah BOWL-sah djee SANG-ghee es-TAH PRON-tah

A few notes:

• bolsa sounds roughly like BOWL-sah
• de before sangue often sounds like djee in Brazilian Portuguese
• sangue has a nasal vowel, which English does not really have
• pronta sounds roughly like PRON-tah, with the on slightly nasalized

This is only an approximation, but it can help you get started.

Bolsa has several meanings depending on context. It can mean:

• bag
• purse
• pouch
• scholarship in some contexts (bolsa de estudos)

In this sentence, because of de sangue, it clearly means a medical blood bag.

So context is what tells you which meaning is intended.

Yes, it sounds natural and clear in a medical context.

A Brazilian Portuguese speaker would understand A bolsa de sangue está pronta as meaning that the blood bag has been prepared and is ready.

Depending on the exact situation, professionals might also use more technical or context-specific phrasing, but this sentence itself is perfectly understandable and natural.