Ik herken zijn gezicht.

Herkennen means to recognize: you see, hear, or notice something and realize you know it from before.

By contrast, kennen usually means to know or to be familiar with.

• Ik ken hem = I know him
• Ik herken hem = I recognize him

So in Ik herken zijn gezicht, the idea is that the face looks familiar and you realize whose face it is.

Because herkennen is the infinitive, meaning to recognize.

In a normal present-tense sentence with ik, Dutch uses the verb stem:

• infinitive: herkennen
• stem: herken
• sentence: Ik herken zijn gezicht

This is the regular pattern for many verbs:

• werken → ik werk
• horen → ik hoor
• herkennen → ik herken

Here, zijn means his.

Dutch zijn can be two different things:

• a verb: zijn = to be
• a possessive word: zijn = his

In Ik herken zijn gezicht, it is clearly the possessive, because it comes before the noun gezicht and describes whose face it is.

So:

• zijn gezicht = his face

Because zijn already functions like a determiner, so it takes the place of de or het.

Dutch normally uses:

• het gezicht = the face
• zijn gezicht = his face

But not:

• het zijn gezicht

This works the same way as in English: you say his face, not the his face.

Gezicht is a het word:

• het gezicht = the face

That matters when there is no possessive:

• Ik herken het gezicht = I recognize the face

Its plural is gezichten, and plurals take de:

• het gezicht
• de gezichten

This is the normal Dutch main-clause word order:

• subject: Ik
• finite verb: herken
• object: zijn gezicht

So it follows the common pattern subject + verb + object.

Dutch also has the verb-second rule in main clauses, which means the finite verb comes in the second position. In this sentence, the subject is first, so the verb comes right after it:

• Ik herken zijn gezicht

If you move another element to the front, the verb still stays second:

• Vandaag herken ik zijn gezicht

A rough guide:

• Ik ≈ ik
• herken ≈ hehr-KEN
• zijn ≈ something like zayn, though Dutch ij is not exactly the same as English ay
• gezicht ≈ guh-ZIKHT, with the Dutch guttural g and ch

A few tricky points for English speakers:

• ij in zijn is a Dutch vowel sound that does not match English perfectly
• g in gezicht is usually a throaty sound in standard Dutch
• ch in gezicht is also a harsh throat sound
• the stress is on -ken in herken and on zicht in gezicht

No. Herkennen is an inseparable verb.

That means the prefix her- stays attached to the verb:

• Ik herken zijn gezicht
• Ik heb zijn gezicht herkend

Not:

• Ik ken zijn gezicht her

This is important because some Dutch verbs do split apart, but herkennen does not.

To make it negative, add niet:

• Ik herken zijn gezicht niet. = I do not recognize his face.

To make it a yes-no question, put the verb first:

• Herken ik zijn gezicht? = Do I recognize his face?

These are very common Dutch patterns:

• statement: Ik herken zijn gezicht.
• negative: Ik herken zijn gezicht niet.
• question: Herken ik zijn gezicht?

You could, but it does not mean exactly the same thing.

• Ik herken zijn gezicht = I recognize his face right now
• Ik ken zijn gezicht = I know his face / his face is familiar to me

So herkennen is about the moment of recognition, while kennen is more about existing familiarity.

In many situations, herkennen is the better match for English recognize.

Yes. In informal spoken Dutch, zijn is often reduced to z'n.

So you may hear:

• Ik herken z'n gezicht.

That still means the same thing: I recognize his face.

In careful writing, zijn gezicht is the standard full form.