Břeh je vedle koryta.

Because vedle normally requires the genitive case.

The basic dictionary form is koryto. It is a neuter noun, and its genitive singular form is koryta.

So:

• koryto = nominative singular, basic form
• koryta = genitive singular

After vedle (next to / beside), Czech uses the genitive:

• vedle koryta = next to the riverbed / channel / trough

This is a very common thing to memorize with Czech prepositions: each preposition tends to require a specific case.

Břeh is in the nominative singular.

In this sentence, břeh is the subject, and subjects are normally in the nominative case.

So the structure is:

• břeh = the subject
• je = is
• vedle koryta = a prepositional phrase meaning next to the riverbed/channel

Je is the 3rd person singular present tense of the verb být (to be).

So here it simply means is.

A quick comparison:

• jsem = I am
• jsi / jste = you are
• je = he/she/it is
• jsme = we are
• jsou = they are

In Břeh je vedle koryta, je links the subject břeh with the location phrase vedle koryta.

The word order can be changed, because Czech word order is more flexible than English word order.

The sentence Břeh je vedle koryta is a neutral, straightforward version.

You could also say:

• Vedle koryta je břeh.

This still means basically the same thing, but the emphasis shifts a little. It may sound more like Next to the riverbed, there is a bank or it highlights the location first.

So:

• Břeh je vedle koryta. = neutral
• Vedle koryta je břeh. = location emphasized first

Czech word order often depends on focus, emphasis, and context, not just grammar.

The hardest part for most English speakers is ř.

A rough guide:

• břeh sounds approximately like brzheh, but that is only an approximation
• ř is a special Czech sound, something like a mix of r and zh (the sound in measure)

Important points:

• b = like English b
• ř = unique Czech sound
• e = like e in bed, but a bit cleaner
• h = pronounced, unlike English silent h

So břeh ends with a real h sound.

If a learner cannot say ř yet, using a plain r is a common beginner substitute, though it is not fully correct.

Vedle means next to, beside, or alongside, depending on context.

In this sentence, it expresses location:

• vedle koryta = next to the riverbed/channel

It is a very common preposition in Czech.

Examples:

• dům je vedle školy = the house is next to the school
• sedí vedle mě = he/she is sitting next to me

When vedle is used as a preposition, it normally takes the genitive.

Yes, but its meaning depends on context.

Koryto can mean:

• a riverbed
• a channel
• a trough (for animals, for example)

In the sentence Břeh je vedle koryta, the most natural interpretation is something like riverbed or channel, because břeh means bank / shore.

So the pair břeh + koryto strongly suggests a landscape or water-related meaning.

Czech does not use articles the way English does.

So Czech does not have direct equivalents of:

• a
• an
• the

That means Břeh je vedle koryta could be translated in English in different ways depending on context, for example:

• The bank is next to the riverbed.
• A bank is next to the riverbed.

English must choose an article, but Czech usually leaves that information to context.

Břeh is a masculine inanimate noun.

That matters because Czech nouns belong to grammatical genders, and gender affects:

• adjective endings
• pronouns
• case endings
• some numeral forms

For this sentence, the key point is simply that břeh is masculine and appears here in the nominative singular.

Yes, but then it is not working as a normal preposition.

As a preposition, vedle needs a noun phrase in the genitive:

• vedle koryta
• vedle domu
• vedle školy

But in some contexts, vedle can also function more like an adverb or part of a fixed expression meaning beside / in addition / off to the side.

For a learner, the safest rule is:

• if vedle means next to and is followed by a noun, use the genitive

It can be understood as either, depending on context.

Czech je vedle koryta simply states location. It does not by itself clearly distinguish between:

• a permanent fact
• a temporary situation

So it could mean:

• the bank is located next to the riverbed as a general fact
• in this scene or description, the bank is next to the channel

Context tells you which interpretation is intended. This is similar to English is next to.

Good question, because koryta can look ambiguous to beginners.

For koryto, the form koryta can be:

• genitive singular
• or nominative/accusative plural

But here, after vedle, it must be genitive singular, because vedle requires the genitive.

So grammar tells you the number and case here.

This is very common in Czech: the same form can have more than one grammatical function, and the surrounding words help you identify the correct one.