Eu não conheço esses amigos.

You can leave out Eu.

Portuguese is a “pro‑drop” language: the verb ending -o in conheço already tells you the subject is I.

So you can say:

• Eu não conheço esses amigos.
• Não conheço esses amigos. ✅ (very natural)

You only keep Eu if you want to emphasise “I” (e.g. I don’t know those friends, but someone else does).

In Portuguese, não normally goes directly before the verb it negates.

• Eu não conheço esses amigos. = I don’t know those friends.

You cannot move it to the end like in some casual English:

• ❌ Eu conheço esses amigos não.

In neutral sentences, the pattern is:
[subject] + não + [verb] + [rest of the sentence].

Very roughly:

• conhecer = to know / be acquainted with (people, places, things you’re familiar with)
• saber = to know (information / facts / how to do something)

Examples:

• Eu não conheço esses amigos.
  I’m not acquainted with those friends / I don’t know them personally.

• Eu sei a resposta.
  I know the answer. (a piece of information)

• Eu sei falar português.
  I know how to speak Portuguese.

With people, you normally use conhecer, not saber.

No, that’s incorrect in Portuguese.

With friends / people, you need conhecer, not saber:

• ✅ Eu não conheço esses amigos.
• ❌ Eu não sei esses amigos.

Using saber here sounds ungrammatical to a native speaker.

In European Portuguese, esses usually corresponds to “those” (near the listener), not “these”.

Very simplified:

• estes amigos = these friends (near me, the speaker)
• esses amigos = those friends (near you, the listener, or just mentioned)
• aqueles amigos = those friends over there (far from both of us)

In your sentence, esses amigos is like “those friends (you’re talking about / you know)”.

In European Portuguese (PT‑PT):

• estes amigos – “these friends”

  • Physically close to the speaker, or just introduced by the speaker.

• esses amigos – “those friends”

  • Close to the listener, or already known in the conversation context.

• aqueles amigos – “those friends over there”

  • Far from both speaker and listener (physically or mentally / in the story).

So:

• Eu não conheço estes amigos.
  I don’t know these friends (near me).

• Eu não conheço esses amigos.
  I don’t know those friends (you’re referring to).

• Eu não conheço aqueles amigos.
  I don’t know those friends (over there / from that group).

You don’t use a normal definite article (o, a, os, as) together with a demonstrative like este/esse/aquele.

The demonstrative already acts like a determiner, so you say:

• ✅ esses amigos
• ❌ os esses amigos

You can combine a demonstrative with a possessive, though:

• esses teus amigos = those friends of yours

Both the demonstrative and the noun must agree in gender (masculine/feminine) and number (singular/plural):

• esse amigo – that (male) friend
• essa amiga – that (female) friend
• esses amigos – those (male or mixed group) friends
• essas amigas – those (female) friends

In your sentence, esses amigos is masculine plural, so esses matches amigos.

You can say:

• Eu não conheço esses teus amigos.
  (literally: “I don’t know those your friends.”)

This structure demonstrative + possessive + noun (e.g. esses teus amigos) is very common and natural in European Portuguese.

Conheço is present indicative, 1st person singular of conhecer:

• (eu) conheço = I know / I am acquainted with

Portuguese usually uses this simple present for what English also expresses with simple present:

• Eu não conheço esses amigos.
  I don’t know those friends.

You would not normally say something like “estou a conhecer esses amigos” to mean “I’m getting to know them” unless you really mean an ongoing, developing process (and even then, a different wording is more common).

You replace esses amigos with the direct object pronoun os (masculine plural):

• Eu não os conheço.
  = I don’t know them.

Notice the position:

• não comes first,
• then os (the pronoun),
• then conheço (the verb).

In European Portuguese, with não, the clitic pronoun must come after não and before the verb:
✅ Eu não os conheço.
❌ Eu não conheço-os.

In a careful but natural European Portuguese pronunciation:

• Eu não conheço esses amigos.
  roughly: “eh-o nawn ku-NEH-su EH-sish a-MI-gush”

More phonetic (IPA-style) approximation:
[eu̯ ˈnɐ̃w̃ kuˈne.su ˈɛ.sɨʃ ɐˈmi.ɣuʃ]

Some key points:

• ão in não is a nasal sound, similar to French on but with more mouth opening.
• The final s in esses and amigos is pronounced like English “sh” in European Portuguese: [ʃ].
• r is soft here (there is no r in this sentence, but in related forms like conhecer, it would be a soft sound at the end).