La hoja de laurel le da mucho sabor a las lentejas.

It literally means the leaf of laurel, but in cooking it means the bay leaf.

• hoja = leaf
• laurel = laurel / bay tree

So una hoja de laurel = a bay leaf.

Because the main noun is hoja, and hoja is feminine.

In la hoja de laurel, the part de laurel just tells you what kind of leaf it is. The article agrees with hoja, not with laurel.

So:

• la hoja
• el laurel = the laurel tree / bay

Because the subject is singular: La hoja de laurel.

Spanish verbs agree with the subject:

• La hoja de laurel da... = one bay leaf gives...
• Las hojas de laurel dan... = bay leaves give...

So da is the correct 3rd person singular form of dar.

Le is an indirect object pronoun.

With dar, Spanish often works like this:

• someone/something gives
• something = direct object
• to someone/something = indirect object

Here:

• La hoja de laurel = subject
• mucho sabor = what is being given
• a las lentejas = the receiver

So le means something like to it / to them in this structure.

Yes, from an English point of view it feels repetitive, but this is very common in Spanish. It is called indirect object doubling.

Spanish often uses:

• le/les
  • verb + a...

So you can get:

• Le da mucho sabor a las lentejas

Even though a las lentejas is already there, the pronoun is still commonly used.

English usually would not double it this way.

In standard Spanish, yes: many teachers and grammar books would expect les because las lentejas is plural.

So the form learners should normally use is:

• La hoja de laurel les da mucho sabor a las lentejas.

You may hear le in everyday speech from some speakers, but les is the safer standard choice.

Because a las lentejas is the indirect object after dar.

This is not the personal a. It is just part of the pattern:

• dar algo a alguien/algo = to give something to someone/something

So:

• da mucho sabor a las lentejas = gives a lot of flavor to the lentils

Because mucho is used with nouns, and sabor is a noun.

• mucho sabor = a lot of flavor

But muy is used with adjectives and adverbs:

• muy sabroso = very tasty
• muy bien = very well

So:

• mucho sabor ✅
• muy sabor ❌

Spanish often uses the definite article with foods and dishes more than English does.

Here las lentejas probably refers to:

• the lentils being cooked
• or the lentil dish as a whole

Also:

• lenteja = one lentil
• lentejas = lentils

So las lentejas is very natural here.

Yes. You can also say:

• La hoja de laurel da mucho sabor a las lentejas.

That is grammatical and natural.

With le/les, the sentence sounds more like the common Spanish pattern with an indirect object. If you want the safest standard version with the pronoun, use:

• La hoja de laurel les da mucho sabor a las lentejas.

Yes. It is a very useful pattern:

• X da sabor a Y
• X le/les da sabor a Y

Examples:

• El ajo le da mucho sabor a la sopa.
• El chorizo les da mucho sabor a las lentejas.
• La cebolla le da buen sabor al arroz.

So this sentence is a good model for talking about cooking and ingredients.