A defesa da equipa é forte.

A is the feminine singular definite article, meaning the.

It is used because defesa is a feminine singular noun, so the article must match it:

• a defesa = the defence
• o ataque = the attack

In Portuguese, articles are used very often, sometimes more often than in English.

In Portuguese, every noun has a grammatical gender, usually masculine or feminine. Defesa is a feminine noun, so it takes feminine words with it:

• a defesa
• a defesa forte

This is grammatical gender, not biological gender. It is simply part of how the noun behaves in the language.

Da is a contraction of de + a:

• de = of
• a = the
• de + a = da

So:

• a defesa da equipa = the team’s defence / the defence of the team

This contraction is required in normal Portuguese. You would not normally say de a equipa.

In European Portuguese, equipa is the standard word for team.

So in Portugal, you would usually say:

• a equipa

In Brazilian Portuguese, time is also very common in sports contexts. A learner of Portuguese from Portugal should prefer equipa.

É is the 3rd person singular of the verb ser:

• eu sou
• tu és
• ele/ela é

It is used because the subject is a defesa, which is singular.

So:

• A defesa ... é forte = The defence ... is strong

Also, é has an accent to distinguish it from e, which means and.

Portuguese often distinguishes between ser and estar:

• ser = used for characteristics seen as essential, defining, or stable
• estar = used for states or conditions seen as temporary

In A defesa da equipa é forte, é forte describes the team’s defence as a general characteristic, so ser is the natural choice.

If you said está forte, it would suggest something more temporary, like the team’s defence is currently performing strongly.

In Portuguese, adjectives often come after the noun.

So:

• a defesa forte = the strong defence

In this sentence, the adjective comes after the verb because it is part of the predicate:

• A defesa da equipa é forte
• literally: The defence of the team is strong

This word order is completely normal.

Some Portuguese adjectives change form for gender:

• alto / alta
• bonito / bonita

But forte is an adjective with the same form for masculine and feminine singular:

• o jogador forte
• a defesa forte

It only changes clearly in the plural:

• forte = singular
• fortes = plural

So:

• A defesa da equipa é forte
• As defesas das equipas são fortes

A careful European Portuguese pronunciation would be roughly:

A defesa da equipa é forte
≈ uh duh-FEH-zuh duh ih-KYAH-puh eh FOR-tuh

A few useful notes:

• defesa has stress on fe
• equipa has stress on qui
• é is pronounced like eh
• European Portuguese often reduces unstressed vowels, so some vowels sound weaker than in Brazilian Portuguese

If you say it slowly and clearly, that is perfectly fine as a learner.

Yes. That is also a very natural sentence.

• A defesa da equipa é forte = The team’s defence is strong
• A equipa tem uma defesa forte = The team has a strong defence

They are very close in meaning. The first describes the defence directly; the second describes the team as possessing that quality. Both are good Portuguese.