הגיבור בסרט הזה נראה רגוע, אבל הגיבורה שלו הרבה יותר אמיצה ממנו.

They are the masculine and feminine forms of the same basic noun:

• גיבור = hero, male hero
• גיבורה = heroine, female hero

So:

• הגיבור = the hero
• הגיבורה = the heroine

The ה־ at the beginning is the definite article, meaning the.

Because in Hebrew, short prepositions like ב־ (in) attach directly to the word that follows.

So:

• ב־ = in
• הסרט = the movie

Together they become:

• בסרט = in the movie

This is very common in Hebrew. The same thing happens with other prepositions too:

• לספר = to the book
• מהבית = from the house

So בסרט הזה means in this movie.

That is normal Hebrew word order. Demonstratives like הזה (this, masculine singular) usually come after the noun.

So Hebrew says:

• הסרט הזה = literally the movie this

But it means:

• this movie

The demonstrative also agrees with the noun:

• הסרט הזה = this movie (masculine singular)
• הילדה הזאת = this girl (feminine singular)

Here נראה means seems or looks.

So נראה רגוע means:

• seems calm
• looks calm

It comes from the verb להיראות = to seem / to appear / to look.

In context, it does not mean simply is seen. It describes how the hero appears to others.

Because adjectives in Hebrew must agree with the noun in gender and number.

• הגיבור is masculine singular, so the adjective is masculine singular: רגוע
• הגיבורה is feminine singular, so the adjective is feminine singular: אמיצה

This is a very important Hebrew pattern.

For example:

• ילד רגוע = a calm boy
• ילדה רגועה = a calm girl
• איש אמיץ = a brave man
• אישה אמיצה = a brave woman

Because in the present tense, Hebrew usually leaves out the verb to be.

So where English says:

• the heroine is much braver than him

Hebrew simply says:

• הגיבורה שלו הרבה יותר אמיצה ממנו

There is no separate present-tense word for is here.

This is completely normal in Hebrew:

• הוא עייף = he is tired
• היא חכמה = she is smart

But in past and future, Hebrew does use forms of to be when needed.

שלו means his or its, depending on context.

In this sentence, it most naturally refers to הסרט (the movie), so:

• הגיבורה שלו = its heroine / the movie’s heroine

Hebrew does not have a separate neuter possessive like English its, so the same form שלו can mean both his and its.

Even though שלו is grammatically masculine, that does not mean the thing possessed is masculine. It agrees with the possessor, not the possessed.

יותר means more, and הרבה יותר means much more.

So:

• אמיצה = brave
• יותר אמיצה = braver / more brave
• הרבה יותר אמיצה = much braver

Hebrew often forms comparisons this way:

• יותר גדול = bigger
• יותר יפה = prettier / more beautiful
• הרבה יותר קשה = much harder

Unlike English, Hebrew usually does not change the adjective itself into a comparative form. It adds יותר before it.

ממנו means than him here.

After a comparison with יותר, Hebrew often uses מ־ plus a pronoun:

• ממני = than me
• ממך = than you
• ממנו = than him / than it
• ממנה = than her

So:

• הרבה יותר אמיצה ממנו = much braver than him

The same form ממנו can also mean from him in other contexts, but here the comparison makes the meaning clearly than him.

Yes, it is one word.

It is made from:

• מ־ = from / than
• מנו / הוא-related pronoun form = him

So ממנו is the standard fused form meaning from him or than him.

You should learn these as set forms, because they are used all the time:

• ממני = from me / than me
• ממך = from you / than you
• ממנו = from him / than him
• ממנה = from her / than her

Grammatically, ממנו could mean than him or than it, because Hebrew uses the same form for masculine singular him/it.

But in this sentence, the meaning strongly points to the hero:

• the hero seems calm, but the heroine is much braver than him

So the comparison is between הגיבורה and הגיבור, not between the heroine and the movie.

Context usually tells you which one is meant.

Hebrew often expresses possession very simply with של forms:

• שלי = my/mine
• שלך = your/yours
• שלו = his/its
• שלה = her/hers

So הגיבורה שלו is a natural way to say his heroine or its heroine.

Hebrew could also express possession in other ways, but this של structure is extremely common and very useful in everyday language.

Yes. It is very natural.

The structure is:

• הגיבור בסרט הזה = the hero in this movie
• נראה רגוע = seems calm
• אבל = but
• הגיבורה שלו = its heroine
• הרבה יותר אמיצה ממנו = much braver than him

A native English speaker may notice that Hebrew often puts modifiers after the noun and leaves out is in the present tense, but the sentence itself is completely standard Hebrew.