En el sótano hay un trastero pequeño donde mi abuelo guarda cosas viejas.

Spanish often puts the location first to set the scene. So En el sótano means in the basement, and then the sentence tells you what is there.

This structure is very natural in Spanish:

• En el sótano hay... = In the basement there is...
• En la cocina hay... = In the kitchen there is...

You could also say Hay un trastero pequeño en el sótano, but the original version sounds more descriptive and natural in many contexts.

Because sótano is a masculine singular noun, and here it needs the definite article el.

• en = in
• el sótano = the basement
• en el sótano = in the basement

In Spanish, articles are used more often than in English, so leaving out el here would sound incorrect.

Hay is used to say that something exists or there is/there are something somewhere.

• En el sótano hay un trastero pequeño = There is a small storage room in the basement

Use está when you are talking about the location of something specific:

• El trastero está en el sótano = The storage room is in the basement

So:

• hay = introduces something as existing
• está/están = says where a known thing is

In Spanish, adjectives usually come after the noun, so trastero pequeño is the normal order.

• un trastero pequeño = a small storage room

You can sometimes put the adjective before the noun, but that often changes the tone or emphasis. In this sentence, the neutral, standard order is noun + adjective.

In Spain, trastero usually means a storage room, storage space, or box room where people keep things they do not use often.

It is a very common word in Spain. In other Spanish-speaking countries, other words may be more common depending on the region.

So here, un trastero pequeño is a small room or space used for storage.

Donde means where and introduces a relative clause that gives more information about el trastero.

• un trastero pequeño donde mi abuelo guarda cosas viejas
• a small storage room where my grandfather keeps old things

It connects the place (trastero) with what happens there (mi abuelo guarda cosas viejas).

You could think of it as:

• where my grandfather keeps old things

Yes. A more formal or more explicit version would be:

• En el sótano hay un trastero pequeño en el que mi abuelo guarda cosas viejas.

This also means where my grandfather keeps old things.

Both are correct, but donde is simpler and more natural here because it refers to a place.

Spanish often leaves out subject pronouns like él, ella, yo, etc., because the verb ending already shows who the subject is.

Here, though, the subject is given explicitly as mi abuelo:

• mi abuelo guarda = my grandfather keeps/stores

You do not need él because mi abuelo already tells you who does the action.

Here guarda comes from guardar, which can mean:

• to keep
• to store
• to put away

In this sentence, guarda cosas viejas means that the grandfather keeps/stores old things in the storage room.

This is not guardar in the sense of to save money only; it is more about putting things away and keeping them somewhere.

Because the sentence is talking about old things in a general, indefinite way, not about specific old things already known to the listener.

• guarda cosas viejas = he keeps old things
• guarda las cosas viejas = he keeps the old things / those old things

Without las, it sounds more general and natural here.

Because adjectives in Spanish agree with the noun they describe.

The noun is cosas:

• singular: cosa
• plural: cosas
• feminine noun

So the adjective must match:

• vieja for singular feminine
• viejas for plural feminine

That is why you get:

• cosas viejas = old things

Because hay does not change for singular or plural. It is the same form for both there is and there are.

Examples:

• Hay un trastero = There is a storage room
• Hay dos trasteros = There are two storage rooms

So hay stays the same no matter how many things follow it.

Each adjective matches the noun it describes:

• pequeño describes trastero

  • trastero is masculine singular
  • so: pequeño

• viejas describes cosas

  • cosas is feminine plural
  • so: viejas

This agreement is a basic rule in Spanish.

Yes, in most cases sótano means basement.

So:

• En el sótano = In the basement

In this sentence, it refers to the lower part of a building where the small storage room is located.

Mi is a possessive adjective meaning my.

• mi abuelo = my grandfather

Like English my, it comes before the noun. Unlike English, Spanish possessive adjectives usually do not need an article before the noun in this kind of phrase.

So you say:

• mi abuelo not
• el mi abuelo

If you wanted to focus on the location of the storage room, you could say:

• El trastero pequeño está en el sótano, donde mi abuelo guarda cosas viejas.

That means:

• The small storage room is in the basement, where my grandfather keeps old things.

This version is correct, but it is slightly different in focus:

• hay introduces something that exists
• está locates something specific

The original sentence sounds like you are introducing the storage room for the first time.