Houd je tas stevig vast in de metro.

Yes. The full verb is vasthouden, meaning to hold on to / to keep hold of.

Dutch has many separable verbs. In a main clause, the verb is often split into:

• the conjugated verb: houd
• the particle: vast

So:

• Ik houd mijn tas vast. = I hold my bag tightly / I keep hold of my bag.
• Houd je tas vast. = Hold on to your bag.

In this sentence, stevig is placed between them:

• Houd je tas stevig vast.

That is completely normal in Dutch.

Houd is the imperative form here: a command to one or more people in everyday language.

The base verb is houden. The common imperative is:

• Houd! = Hold!

You may also hear hou in speech, but houd is generally the safer standard written form.

It is not houdt, because houdt is usually a present-tense form used with jij/u/hij/zij/het in certain patterns, not the normal imperative here.

So:

• Jij houdt je tas vast. = You hold your bag.
• Houd je tas vast! = Hold your bag!

Because this is an imperative sentence, a command. In Dutch, as in English, the subject is usually left out in commands.

Compare:

• You hold your bag tightly. → statement
• Hold your bag tightly! → command

Dutch works the same way:

• Jij houdt je tas stevig vast. → statement
• Houd je tas stevig vast. → command

You can add a subject for emphasis sometimes, but normally you do not.

Here je means your.

So:

• je tas = your bag

Dutch je can mean different things depending on the sentence:

• je as a subject/object pronoun = you
• je as a possessive determiner = your

In Houd je tas stevig vast, it is possessive, because it comes directly before the noun tas.

Both are possible, but they are not used in exactly the same way.

• je tas = normal, unstressed your bag
• jouw tas = stressed or emphatic your bag

So the sentence given is the most natural neutral version:

• Houd je tas stevig vast in de metro.

If you wanted emphasis, for example contrasting with someone else’s bag, you could say:

• Houd jouw tas stevig vast. = Hold your bag tightly.

Native speakers usually choose je unless they want extra stress or contrast.

Here stevig means something like:

• firmly
• tightly
• securely

It tells you how to hold the bag.

So:

• Houd je tas vast. = Hold on to your bag.
• Houd je tas stevig vast. = Hold on to your bag firmly/tightly.

Stevig often means firm, solid, or sturdy, but in this sentence it works like an adverb describing the action.

In this sentence, vast is the particle that belongs to vasthouden.

On its own, vast can have meanings like:

• fixed
• stuck
• firm
• secure

But in vasthouden, it helps create the meaning to keep hold of.

So you should not translate houd and vast too separately here. Together they form the idea:

• vasthouden = to hold on to / to keep hold of

That is why stevig vast feels natural: firmly hold on to.

Because stevig modifies the action, and vast is the separable particle of the verb.

The normal order is:

• Houd
  • object + adverb + vast

So:

• Houd je tas vast.
• Houd je tas stevig vast.
• Houd je tas goed vast.

This is a very common pattern with separable verbs in Dutch.

In de metro means in the metro / on the subway.

Dutch often uses in for being inside a vehicle or transport system:

• in de trein = on the train
• in de bus = on the bus
• in de metro = on the metro / subway

English often says on the train/bus, but Dutch commonly uses in because the idea is physically inside the vehicle.

Also, metro is a de-word, so:

• de metro
• not het metro

In everyday Dutch, this imperative can be used very naturally for both:

• one person
• a general audience
• a group

So Houd je tas stevig vast in de metro can work as a general instruction like a public announcement.

If you want to be more formal or polite to one person, you could say:

• Houd uw tas stevig vast in de metro.

With uw, it sounds more formal.

Not exactly.

• Houd je tas stevig vast = keep holding your bag tightly
• Pak je tas stevig vast = grab your bag tightly

Pak focuses more on the moment of taking hold of something.
Houd ... vast focuses more on maintaining your grip.

In a warning or safety context, Houd je tas stevig vast is the more natural choice.

Yes, you may hear or see hou instead of houd, especially in informal language.

So both occur:

• Houd je tas stevig vast.
• Hou je tas stevig vast.

But if you are learning standard written Dutch, houd is a good form to use.

A statement version would need a subject and normal verb conjugation, for example:

• Je houdt je tas stevig vast in de metro. = You hold your bag tightly in the metro.
• Ik houd mijn tas stevig vast in de metro. = I hold my bag tightly in the metro.

This helps show the difference:

• houd = imperative
• houdt/houd in a statement = finite verb with a subject

So the command form is simply the same idea without the subject:

• Houd je tas stevig vast in de metro.