המשטרה מתחילה פעולה.

ה־ is the Hebrew definite article, the equivalent of the. It is attached directly to the noun.

• משטרה = police / a police force
• המשטרה = the police

So Hebrew uses a prefix here instead of a separate word like English the.

In Hebrew, משטרה is grammatically singular feminine. It refers to the police as one institution, not as a group of individual officers.

That is why the verb is also singular:

• המשטרה מתחילה = the police is starting / the police starts

If you meant individual police officers, you would use a plural noun such as שוטרים or שוטרות.

Hebrew present-tense verbs agree with the subject in gender and number.

Since המשטרה is feminine singular, the verb must also be feminine singular:

• מתחיל = masculine singular
• מתחילה = feminine singular

So מתחילה matches המשטרה correctly.

מתחילה is the present tense form of להתחיל (to begin / to start).

In Hebrew, the present tense can correspond to several English forms, depending on context, such as:

• starts
• is starting
• is beginning

So this form does not by itself force just one English tense choice.

The dictionary form is להתחיל = to begin / to start.

Useful related forms:

• להתחיל = to begin
• התחיל = he began
• מתחיל = beginning / begins (masculine singular)
• מתחילה = beginning / begins (feminine singular)

This verb belongs to the הפעיל pattern.

Hebrew does not have a separate word for a or an.

A noun without ה־ is usually indefinite:

• פעולה = an action / an operation
• הפעולה = the action / the operation

So the idea of an is understood automatically from the lack of the definite article.

Because את is used before a definite direct object, and פעולה here is indefinite.

Compare:

• המשטרה מתחילה פעולה = the police begins an operation
• המשטרה מתחילה את הפעולה = the police begins the operation

So no את is needed in the original sentence.

פעולה is a broad word. It can mean:

• action
• act
• operation
• activity

In a police context, it often means something like an operation or an action being carried out. The most natural English translation depends on the wider context.

Yes. This is the normal subject–verb–object order:

• המשטרה = subject
• מתחילה = verb
• פעולה = object

That makes the sentence straightforward and neutral in tone.

A simple pronunciation guide is:

ha-mish-ta-RA mat-khi-LA pe-u-LA

A few notes:

• ח in מתחילה is a throaty kh sound, like the ch in Scottish loch or German Bach
• Stress is on the last syllable of each word:
  • ha-mish-ta-RA
  • mat-khi-LA
  • pe-u-LA