הוא הוסיף כף אחת של תבלין למרק, ואז מזג לי עוד קצת מים.

הוא is not strictly necessary. Hebrew often drops subject pronouns when the verb already shows the person, number, and gender.

So both of these are possible:

• הוא הוסיף כף אחת של תבלין...
• הוסיף כף אחת של תבלין...

The form הוסיף already means he added, so the pronoun is optional. Keeping הוא can make the sentence feel a bit clearer, more explicit, or slightly more contrastive, especially in a longer story.

Both are past tense, third person masculine singular:

• הוסיף = he added
• מזג = he poured

They match the subject הוא.

Because כף is a feminine noun, and the number one has to agree with it:

• masculine: אחד
• feminine: אחת

So:

• ספר אחד = one book
• כף אחת = one spoon / one tablespoon

With the number one, Hebrew usually puts the number after the noun:

• ילד אחד = one boy
• ילדה אחת = one girl
• כף אחת = one spoon

This is very normal Hebrew word order.

Here של means of.

So כף אחת של תבלין literally means one spoon of spice/seasoning.

Hebrew often uses של with measure expressions:

• כוס של מים = a glass of water
• כפית של סוכר = a teaspoon of sugar
• כף אחת של תבלין = one spoon of seasoning

Because תבלין here works like a mass noun, similar to seasoning in English.

So כף אחת של תבלין means one spoonful of seasoning/spice mixture.

If you wanted to emphasize separate spices, you could say תבלינים, but in cooking Hebrew, singular תבלין is often natural when talking about seasoning in a general sense.

The preposition ל־ means to, so למרק means to the soup / into the soup.

A useful point: in everyday unpointed Hebrew, למרק can represent either:

• לְמָרָק = to soup
• לַמָּרָק = to the soup

In real-life writing, the difference is usually understood from context. In this sentence, the meaning is clearly to the soup.

ואז means and then or simply then.

• ו־ just means and
• ואז adds a sense of sequence: and then / after that

So it helps show that the second action happened after the first one.

Here מזג means poured.

So מזג לי עוד קצת מים means he poured me a little more water.

This verb is commonly used for pouring liquids, especially when serving someone:

• מזג מים = poured water
• מזג יין = poured wine

It is the preposition ל־ plus the pronoun י:

• ל־ = to / for
• לי = to me / for me

With a verb like מזג, English often translates it as for me:

• מזג לי מים = he poured me water / he poured water for me

So grammatically it is to me, but in natural English for me is often the best translation.

Because את is normally used before a definite direct object, and עוד קצת מים is indefinite.

Compare:

• מזג לי עוד קצת מים = he poured me some more water
  → no את
• מזג לי את המים = he poured me the water
  → את appears because המים is definite

It is made of two parts:

• עוד = more / another
• קצת = a little / some

Together, עוד קצת מים means a little more water or some more water.

This is a very common Hebrew pattern:

• עוד קצת זמן = a little more time
• עוד קצת אוכל = a little more food
• עוד קצת מים = a little more water

Because מים is one of those Hebrew nouns that has a plural-looking form but often refers to a substance as a whole, like water.

So even though it looks plural, you usually translate it as singular water, not waters.

This is similar to a few other Hebrew words for natural substances or paired things whose forms do not match simple English expectations.