Vertemos el agua en el vaso.

Vertemos is the 1st person plural form of the verb verter, so it means we pour.

• verter = to pour
• vierto = I pour
• viertes = you pour
• vierte = he/she/it pours
• vertemos = we pour

This verb is a little less common in everyday speech than verbs like echar, but it is perfectly correct.

Because verter is an -er verb, and in the present tense the nosotros ending is -emos:

• beber → bebemos
• comer → comemos
• verter → vertemos

So vertimos would not be the standard present-tense nosotros form here.

Spanish often leaves out the subject pronoun because the verb ending already tells you who is doing the action.

• Vertemos already means we pour
• So nosotros vertemos el agua en el vaso is possible, but usually unnecessary

Spanish does this much more often than English.

Great question. Agua is grammatically feminine, but in the singular it usually takes el instead of la because it begins with a stressed a sound.

So you say:

• el agua
• el águila
• el aula

But the noun is still feminine, which you can see in adjectives:

• el agua fría = the cold water

And in the plural, it goes back to normal feminine articles:

• las aguas

Because en is the normal preposition for in / into / inside in sentences like this.

• Vertemos el agua en el vaso = We pour the water into the glass

Spanish often uses en where English uses in or into, depending on context.

Also, a el normally contracts to al, but that is not what this sentence needs. En el vaso is the natural choice here.

Here it is understood as into because the verb verter implies movement of the water from one place to another.

So although en often translates as in, in this sentence the natural English meaning is:

• We pour the water into the glass

This is very common in Spanish: the preposition stays simple, and the verb gives the sense of movement.

Vaso usually means glass or drinking glass. Depending on context, it can sometimes be translated more generally, but here glass is the most natural meaning.

Compare:

• vaso = glass, tumbler
• taza = cup (like a tea or coffee cup)
• copa = wine glass / goblet

So en el vaso most naturally means into the glass.

Yes. Vertemos is in the present indicative.

In Spanish, the simple present can often translate as:

• we pour
• we are pouring

depending on context.

If you specifically wanted to emphasise an action in progress, Spanish could also use:

• Estamos vertiendo el agua en el vaso

But the simple present sentence is completely normal.

Yes, but in everyday conversation many speakers would more often say echar for something like this.

For example:

• Echamos el agua en el vaso

That sounds very natural in everyday Spanish.
Verter is still correct and useful, and it can sound a bit more precise or formal depending on context.

Yes, Spanish word order is flexible, though the original order is the most neutral:

• Vertemos el agua en el vaso

Other orders are possible for emphasis, for example:

• El agua la vertemos en el vaso
• En el vaso vertemos el agua

These are more marked and depend on context. For a learner, the original sentence is the best basic pattern.

In Spanish from Spain, v and b are generally pronounced the same or very similarly. So verter does not sound like the strong English v in very.

A rough pronunciation is:

• ber-TEHR

The r is a Spanish tapped r, not an English r.

So for many learners, the key point is:

• Spanish v is usually pronounced like Spanish b
• do not use a strong English v sound

Yes. Since el agua is the direct object, you can replace it with la:

• La vertemos en el vaso. = We pour it into the glass.

Even though agua takes el in the singular, it is still feminine, so the pronoun is la, not lo.

Because the personal a is mainly used with people and sometimes pets or personified beings, not with things like water.

So:

• Vemos a María = We see María
• Vertemos el agua = We pour the water

Since agua is a thing, there is no personal a.