Venid a la cocina, poneos el delantal y probad la salsa.

Because this sentence is giving commands. Spanish uses the imperative for direct instructions.

Here, the speaker is telling a group of people to do three things:

• venid = come
• poneos = put on
• probad = taste / try

So these are not dictionary forms; they are command forms.

These commands are addressed to vosotros, the informal plural you used in Spain.

So the speaker is talking to more than one person in an informal situation, such as friends, family, classmates, or coworkers in a relaxed setting.

That is why you see:

• venid
• poneos
• probad

In most of Latin America, speakers would normally use ustedes instead, with forms such as:

• vengan
• pónganse
• prueben

For regular vosotros affirmative commands, you usually:

1. take the infinitive
2. remove the final -r
3. add -d

So:

• venir → venid
• probar → probad

This is the normal pattern for affirmative vosotros commands.

Because the vosotros affirmative imperative is based on the infinitive pattern, not on the stem-changing present-tense forms.

Even though probar has stem changes in some forms:

• yo pruebo
• tú pruebas

the vosotros command is still:

• probad

So stem-changing verbs often do not keep the stem change in this form.

Because this is a reflexive vosotros affirmative command.

The basic command of poner for vosotros is:

• poned

Then you add the reflexive pronoun os:

• poned + os

But with affirmative vosotros reflexive commands, the final -d is usually dropped before os:

• poned + os → poneos

So poneos means put on yourselves or more naturally put on.

In Spanish, affirmative commands attach object and reflexive pronouns to the end of the verb.

So:

• poneos = put on yourselves

But in a negative command, the pronoun goes before the verb:

• no os pongáis

This contrast is very common:

• affirmative: pronoun attached
• negative: pronoun before the verb

That is a very common point of confusion.

The verb poner is irregular in some command forms:

• tú: pon
• usted: ponga
• ustedes: pongan

But the vosotros affirmative form follows the usual pattern:

• poner → poned

Then with the reflexive pronoun:

• poned → poneos

So even irregular verbs can look quite regular in the vosotros affirmative imperative.

Because Spanish normally uses a to indicate movement toward a destination.

So:

• venir a = to come to
• ir a = to go to

That is why you get:

• Venid a la cocina = Come to the kitchen

The a marks where the people should come.

Spanish often uses the definite article with clothing, especially when the item is understood from the situation.

So poneos el delantal literally says put on the apron, but in natural English we may think of it as put on your apron.

This is very common with clothes and body-related things:

• Ponte el abrigo = Put on your coat
• Lavaos las manos = Wash your hands

Spanish often prefers the where English prefers your.

Because the sauce is being treated as a specific, known sauce in the situation.

If everyone is cooking together and there is one sauce they are working on, Spanish naturally uses the definite article:

• probad la salsa = taste the sauce

Using una salsa would usually suggest some sauce / a sauce, not the specific one already present in the context.

Yes, it strongly sounds like Spanish from Spain because of the vosotros command forms:

• venid
• poneos
• probad

In most of Latin America, the same idea would more likely be expressed with ustedes:

• Vengan a la cocina, pónganse el delantal y prueben la salsa.

So a learner should recognize this sentence as standard and natural for Spain.