המערכת מחייבת להקליד קוד חדש.

Because the subject is המערכת (the system), and מערכת is a feminine singular noun in Hebrew.

So the verb has to agree with it:

• המערכת מחייבת = the system requires
• If the subject were masculine, you would expect מחייב

This is very common in Hebrew: verbs in the present tense agree with the subject in gender and number.

Here, מחייבת means requires, obliges, or makes it necessary.

It comes from the root used in לחייב, which can mean things like:

• to require
• to obligate
• sometimes to charge (for money), in other contexts

In this sentence, the meaning is clearly:

• המערכת מחייבת... = the system requires...

So the context tells you it is not about money here.

להקליד is the infinitive, meaning to type or to enter by typing.

After a verb like מחייבת (requires), Hebrew often uses an infinitive:

• מחייבת להקליד = requires typing / requires [someone] to type

This is similar to English structures like:

• The system requires you to enter...
• The system requires entering...

So להקליד is there because it expresses the action being required.

Hebrew often leaves that kind of subject unstated when it is obvious from context.

So:

• המערכת מחייבת להקליד קוד חדש literally looks like:
• The system requires to type a new code

But natural English supplies the implied person:

• The system requires you to type a new code
• The system requires entering a new code

In many interface or instruction contexts, Hebrew does not explicitly say you if it is already understood that the user is the one acting.

Because קוד חדש is indefinite: it means a new code, not the new code.

In Hebrew, את is used before a definite direct object.

So:

• להקליד קוד חדש = to enter a new code
  no את, because it is indefinite

But:

• להקליד את הקוד החדש = to enter the new code
  uses את, because הקוד החדש is definite

This is a very important Hebrew pattern.

The prefix ה־ is the Hebrew definite article, meaning the.

So:

• המערכת = the system
• קוד חדש = a new code

This sentence mixes a definite subject with an indefinite object, which is very normal:

• The system requires entering a new code

If the object were definite, it would be:

• המערכת מחייבת להקליד את הקוד החדש
  = The system requires entering the new code

In Hebrew, adjectives usually come after the noun they describe.

So:

• קוד חדש = a new code
• literally: code new

This is the normal Hebrew word order for nouns and adjectives.

Also, the adjective must agree with the noun in gender, number, and definiteness:

• קוד חדש = masculine singular
• מערכת חדשה = feminine singular
• הקוד החדש = both noun and adjective are definite

חדש is a masculine singular adjective, because it describes קוד, which is a masculine singular noun.

Compare:

• קוד חדש = a new code
• מערכת חדשה = a new system

So the ending changes depending on the noun.

This is one of the first agreement patterns Hebrew learners need to get used to.

Both can work, depending on context.

Literally, להקליד means to type or to key in.

But in computer/interface language, English often says:

• enter a code instead of
• type a code

So in practice:

• להקליד קוד can mean to type a code
• and in natural UI English often to enter a code

The Hebrew word itself emphasizes the physical act of typing.

A very literal breakdown is:

• המערכת = the system
• מחייבת = requires / obliges
• להקליד = to type / to enter
• קוד = code
• חדש = new

So literally:

• The system requires to type a new code

That is not natural English, but it helps show the Hebrew structure.

A natural English version would be:

• The system requires you to enter a new code or
• The system requires entering a new code

Yes. A few alternatives are possible, depending on style.

For example:

• המערכת דורשת להקליד קוד חדש
  דורשת also means requires/demands

Or more directly to the user:

• יש להקליד קוד חדש
  = A new code must be entered

Or:

• המערכת מחייבת הקלדת קוד חדש
  literally: The system requires the entering of a new code

The original sentence is perfectly natural, especially in system or interface language.