A földszinti tároló olyan kicsi, mint a belső udvar.

Hungarian often leaves out the verb van (is) in the present tense, third person when one noun or adjective is being linked to the subject.

So instead of saying something like A tároló van kicsi, Hungarian simply says:

A tároló kicsi.
= The storage room is small.

That is why in A földszinti tároló olyan kicsi, mint a belső udvar, there is no separate word for is.

If you changed the tense, the verb would appear:

• A tároló kicsi volt. = The storage room was small.
• A tároló kicsi lesz. = The storage room will be small.

A is the definite article, meaning the.

Hungarian has two forms of the definite article:

• a
• az

Which one is used depends on the following sound. Before most consonants, Hungarian uses a. Before vowels, it usually uses az.

So:

• a tároló = the storage room
• az udvar = the courtyard

In your sentence, both noun phrases are definite:

• A földszinti tároló = The ground-floor storage room
• a belső udvar = the inner courtyard

Földszint means ground floor as a noun.
To turn it into an adjective meaning ground-floor or on the ground floor, Hungarian adds -i:

• földszint = ground floor
• földszinti = ground-floor / located on the ground floor

So:

• a földszinti tároló = the storage room on the ground floor

This -i ending is very common in Hungarian for making adjectives from places, locations, institutions, time periods, etc.

Examples:

• budapesti = from Budapest / Budapest
• iskolai = school / related to school
• tavaszi = spring / springtime

Tároló comes from the idea of storage. In everyday Hungarian, it usually means a storage room, storage area, or sometimes a storage unit/locker, depending on context.

So földszinti tároló most naturally means something like:

• ground-floor storage room
• storage room on the ground floor

The exact English wording depends on the building and context.

This is the standard Hungarian pattern for as ... as ... comparisons.

Structure:

olyan + adjective + mint

So:

• olyan kicsi, mint ... = as small as ...

In your sentence:

• olyan kicsi, mint a belső udvar
  = as small as the inner courtyard

More examples:

• Olyan magas, mint az apja. = He is as tall as his father.
• Olyan gyors, mint egy vonat. = It is as fast as a train.

A useful thing to remember is:

• olyan = so / such / that kind of / as
• mint = than / as / like, depending on the structure

Here, together they form the comparison as ... as.

Hungarian has two closely related forms:

• kis — usually used before a noun
• kicsi — often used on its own or after the noun, especially in predicate position

Compare:

• egy kis udvar = a small courtyard
• Az udvar kicsi. = The courtyard is small.

In your sentence, kicsi comes after the subject and describes it, so kicsi is the natural form:

• A tároló kicsi.
• A tároló olyan kicsi, mint...

So a learner should think:

• kis = attributive, before a noun
• kicsi = predicative or standalone, often small

That said, real usage can be a bit flexible, but this is the main pattern to learn first.

Belső means inner or internal.
Udvar means courtyard or yard.

So:

• belső udvar = inner courtyard

This usually refers to the courtyard inside a building block or enclosed residential building, not an outer yard or garden.

Belső is an adjective, and like many Hungarian adjectives, it does not change for gender or number.

Examples:

• belső ajtó = inner door / interior door
• belső tér = interior space
• belső udvar = inner courtyard

Because a belső udvar is also a definite noun phrase: the inner courtyard.

In Hungarian, when you compare two specific things, both can take the definite article if both are definite:

• A tároló olyan kicsi, mint a belső udvar.

This is completely normal. Hungarian does not avoid repeating the the way English sometimes does.

It is in the nominative here, the basic dictionary form.

In simple comparisons with mint, Hungarian often leaves the second item in the same basic form:

• olyan kicsi, mint a belső udvar

Literally, it is something like:

• as small as the inner courtyard

No extra case ending is needed here.

The sentence as given is the most neutral, natural order:

A földszinti tároló olyan kicsi, mint a belső udvar.

Hungarian word order is more flexible than English, but changing the order usually changes the focus or emphasis, not just style.

The neutral structure is:

• subject: A földszinti tároló
• predicate/adjective phrase: olyan kicsi
• comparison: mint a belső udvar

You may see variations in real Hungarian, but for learners this is the best pattern to remember.

A rough pronunciation guide is:

A földszinti tároló olyan kicsi, mint a belső udvar.
≈ aw fuld-sin-tee taa-ro-loo oy-ahn kee-chee mint aw bel-shuh ood-vawr

A few helpful pronunciation points:

• ö / ő / ü / ű are front rounded vowels, which English does not really have
• sz is pronounced like English s
• s is pronounced like English sh
• cs is pronounced like English ch
• gy is a soft consonant, somewhat like dy in duke for some speakers, but not exactly

So:

• földszinti → föld-szin-ti
• kicsi → ki-csi
• belső → bel-ső

Yes, but in natural English you would usually say:

• ground-floor storage room
• storage room on the ground floor

The Hungarian phrase is compact and adjective-based, so a very literal word-for-word rendering may sound slightly incomplete in English. The best English choice depends on context, but grammatically the Hungarian is straightforward:

• földszinti = ground-floor
• tároló = storage room / storage area

It breaks down like this:

• A = the
• földszinti = ground-floor / on the ground floor
• tároló = storage room
• olyan = part of the as ... as structure
• kicsi = small
• mint = as
• a belső udvar = the inner courtyard

So the grammar pattern is:

[Subject] + [olyan + adjective] + [mint + comparison]

Here:

A földszinti tároló + olyan kicsi + mint a belső udvar

That is a very useful pattern you can reuse with other adjectives:

• A szoba olyan világos, mint az iroda. = The room is as bright as the office.
• A kutya olyan barátságos, mint a testvére. = The dog is as friendly as its sibling.