La pescadera me recomendó unas gambas muy frescas.

Pescadera means fishmonger / fish seller and it is the feminine form.

• el pescadero = a male fishmonger
• la pescadera = a female fishmonger

So this sentence tells you that the person who made the recommendation was a woman.

Also, notice the ending:

• -o often marks a masculine noun
• -a often marks a feminine noun

That pattern is very common for jobs and people, though not universal.

Me means to me here.

In La pescadera me recomendó unas gambas muy frescas, the fishmonger recommended the prawns/shrimp to me.

So me is an indirect object pronoun:

• me = to me
• te = to you
• le = to him / to her / to you (formal)

English often says either:

• She recommended some very fresh prawns to me
• She recommended me some very fresh prawns

Spanish normally includes this little pronoun: me.

Recomendó is the preterite form of recomendar for él / ella / usted:

• yo recomendé = I recommended
• tú recomendaste = you recommended
• él / ella / usted recomendó = he / she / you (formal) recommended

The accent mark is important because it shows both pronunciation and verb form.

• recomendó = she/he recommended
• recomendo = not the correct standard form

So the accent helps identify this as a completed action in the past.

Because the subject of the verb is la pescadera, not unas gambas.

Sentence structure:

• La pescadera = the subject
• me recomendó = recommended to me
• unas gambas muy frescas = the thing she recommended

So the verb agrees with la pescadera:

• La pescadera recomendó... = singular subject, singular verb

Even though gambas is plural, it is the object, not the subject.

Unas is the feminine plural form of the indefinite article.

• un = a / one
• una = a / one
• unos = some
• unas = some

Since gambas is feminine plural, you get unas gambas = some prawns/shrimp.

Spanish often uses an article where English might or might not use one. Here, unas gambas sounds very natural, like:

• some prawns
• a few prawns
• some shrimp

If you just said me recomendó gambas, that is possible in some contexts, but unas gambas sounds more like a specific portion or selection being recommended.

In Spain, gambas is a very common word for prawns / shrimp.

Different Spanish-speaking regions use different words:

• Spain: gambas, sometimes langostinos depending on type/size
• Other countries: camarones is often more common

So if you are learning Spanish from Spain, gambas is very normal and useful vocabulary.

Also, the exact English translation can vary a bit because shrimp and prawn do not always match perfectly with Spanish seafood terms.

Because the adjective frescas has to agree with gambas.

• gamba = singular feminine
• gambas = plural feminine

So the adjective must also be plural feminine:

• fresca = fresh (feminine singular)
• frescas = fresh (feminine plural)

That gives:

• unas gambas muy frescas

Also note that muy does not change:

• muy fresco
• muy fresca
• muy frescos
• muy frescas

Muy always stays muy.

Because in Spanish, descriptive adjectives often come after the noun.

So:

• unas gambas muy frescas = some very fresh prawns

This is the most neutral and common word order.

If an adjective comes before the noun in Spanish, it can sometimes sound more literary, subjective, or emphatic, but with something like fresh seafood, the normal order is after the noun:

• gambas frescas

Here, recomendar can take the thing recommended directly, with no preposition:

• Me recomendó unas gambas.
• Nos recomendaron este restaurante.

So unas gambas is the direct object.

The person receiving the recommendation is shown with the indirect object pronoun:

• me = to me

So the pattern is:

• Someone + recomendar + something + to someone
• In Spanish: Alguien + recomendar + algo + a alguien
• Or with pronouns: me, te, le, nos, os, les

That is why me recomendó unas gambas is perfectly normal.

Yes. Spanish word order is more flexible than English, although some orders are more neutral than others.

The original sentence:

• La pescadera me recomendó unas gambas muy frescas.

You could also say:

• Me recomendó unas gambas muy frescas la pescadera.
  This is possible, but less neutral and more marked.
• La pescadera recomendó unas gambas muy frescas.
  This removes me, so now it no longer says to me.
• Unas gambas muy frescas me recomendó la pescadera.
  Possible for emphasis, but not the most basic order.

The original version is the most straightforward and natural for learners.

Yes. That would be a different past tense: the present perfect.

• me recomendó = she recommended / she did recommend
• me ha recomendado = she has recommended

In Spain, the present perfect is often used for past actions connected to the present, especially with time expressions like:

• hoy = today
• esta mañana = this morning
• esta semana = this week

So both are correct, but they are not exactly the same tense.

Because unas gambas is a thing, not a person.

Spanish uses the personal a before specific people (and sometimes pets or personified beings), but normally not before things.

Compare:

• La pescadera vio a María. = The fishmonger saw María.
• La pescadera recomendó unas gambas. = The fishmonger recommended some prawns.

Since gambas are not people, there is no personal a.

You could replace the direct object with las:

• La pescadera me las recomendó.

Here:

• me = to me
• las = them, referring to las gambas

So if the prawns have already been mentioned, Spanish often uses object pronouns instead of repeating the noun.

That is a very common next step after understanding the full sentence.