Repelent je vedle mikiny.

Because vedle normally requires the genitive case.

The base form is mikina. In the genitive singular, it becomes mikiny.

So:

• mikina = sweatshirt / hoodie
• vedle mikiny = next to the sweatshirt / hoodie

This is a very common pattern in Czech: certain prepositions force a specific case, and vedle is one of them.

It is genitive singular.

You can tell this because:

• the dictionary form is mikina
• after vedle, Czech uses the genitive
• feminine nouns like mikina often change to -y in the genitive singular

So the structure is:

• vedle
  • genitive
• vedle mikiny

In normal usage, yes: vedle is followed by the genitive.

Examples:

• vedle domu = next to the house
• vedle auta = next to the car
• vedle mikiny = next to the sweatshirt

So if you learn vedle, it is a good idea to memorize it together with the genitive.

Je is the 3rd person singular form of the verb být, which means to be.

So:

• já jsem = I am
• ty jsi = you are
• on / ona / ono je = he / she / it is

In this sentence, Repelent je vedle mikiny, je means is.

Czech does not have articles like English a, an, or the.

So repelent can mean:

• a repellent
• the repellent

And mikiny in this sentence can be understood as:

• of a sweatshirt
• of the sweatshirt

Which one is meant depends on context. This is completely normal in Czech.

Yes, repelent is a masculine inanimate noun.

You can see that in the nominative singular it looks like many masculine nouns ending in a consonant. In this sentence it stays as repelent because it is the subject.

So:

• repelent = nominative singular
• je agrees with it as a singular subject

Mikina usually means a casual warm top such as a sweatshirt or hoodie.

The exact translation depends on context. In everyday Czech, mikina is often used quite broadly for this type of clothing, whether it has a hood or not.

So in English, depending on the situation, you might translate it as:

• sweatshirt
• hoodie

Yes, Czech word order is more flexible than English word order.

The neutral order here is:

• Repelent je vedle mikiny.

But other orders are possible, for example for emphasis:

• Vedle mikiny je repelent.

That might sound more like Next to the sweatshirt is the repellent or put more focus on the location.

Even though word order can change, the cases still show the grammatical relationships.

A rough English-friendly guide is:

• Repelent ≈ reh-peh-lent
• je ≈ yeh
• vedle ≈ ved-leh
• mikiny ≈ mih-kin-ih

A few useful points:

• j in Czech is pronounced like English y
• e is usually a clear eh
• stress is normally on the first syllable of each word

So the stress pattern is roughly:

• REpelent
• je
• VEDle
• MIkiny

Sometimes, but the meaning is not exactly the same.

• vedle mikiny = next to / beside the sweatshirt
• u mikiny = by / near the sweatshirt

Vedle is more specifically right next to something.
U often means by, at, or near, and is less exact.

So if you want the clear idea of beside, vedle is the better choice here.

Yes. This sentence describes location, not movement.

• Repelent je vedle mikiny. = The repellent is next to the sweatshirt.

There is no idea of going or being placed somewhere. It just says where the repellent is.

If you wanted movement, Czech would usually use a different verb, for example something like dát or položit in a full sentence.