Mému dědečkovi vadí, když je v obchodě moc lidí, proto chodí na trh brzy ráno.

Because the verb vadit works differently from English to bother.

In Czech, the person who is bothered is usually in the dative case, not the nominative. So:

• můj dědeček = my grandfather as the subject
• mému dědečkovi = to my grandfather / my grandfather as the person affected

In this sentence, the structure is basically:

• Mému dědečkovi vadí... = It bothers my grandfather...

So mému dědečkovi is in the dative because he is the experiencer, not the grammatical subject.

Vadí comes from the verb vadit, which means:

• to bother
• to annoy
• to be a problem for

So:

• Mému dědečkovi vadí... = My grandfather is bothered by...
• more literally: ... bothers my grandfather

A very common pattern is:

• Vadí mi to. = It bothers me.
• Vadí ti hluk? = Does noise bother you?
• Nevadí. = It doesn’t matter / No problem.

This is a very common learner question.

In když je v obchodě moc lidí, the verb is often singular because the core expression is moc lidí = a lot of people. Czech often treats quantity expressions like this as a kind of single amount.

So:

• je v obchodě moc lidí = there are too many people in the shop

Even though lidí refers to many people, the structure commonly uses je, not jsou.

You can think of it like:

• There is a lot of people in form, even though natural English says there are a lot of people.

This kind of agreement after quantity expressions is very common in Czech.

Because after moc (a lot of / too much / many), Czech usually uses the genitive.

The noun lidé is the nominative plural form of people, but after moc, you need the genitive plural:

• lidé = people
• lidí = of people

So:

• moc lidí = a lot of people
• málo lidí = few people
• hodně lidí = many people / a lot of people

This is a standard pattern in Czech.

Když means when here.

So:

• když je v obchodě moc lidí = when there are too many people in the shop

It introduces a subordinate clause.

Depending on context, když can also mean:

• when
• sometimes if in more informal or contextual use

But in this sentence, when is the best translation.

Because když introduces a subordinate clause, and Czech normally separates subordinate clauses with a comma.

So the sentence structure is:

• main clause: Mému dědečkovi vadí
• subordinate clause: když je v obchodě moc lidí
• main clause: proto chodí na trh brzy ráno

That is why you see:

• Mému dědečkovi vadí, když...

Czech uses commas more regularly than English in this kind of structure, so it is good to pay attention to them.

Because different places in Czech take different prepositions, and the case changes depending on motion vs location.

1. v obchodě

This means in the shop/store.

• v
  • locative is used for being inside a place
• obchodě is the locative form of obchod

So:

• v obchodě = in the shop

2. na trh

This means to the market.

• na
  • accusative is often used for motion toward places/events/surfaces
• trh here is accusative singular

So:

• chodí na trh = he goes to the market

Compare:

• je v obchodě = he is in the shop (location)
• jde do obchodu = he is going to the shop (motion)

and

• je na trhu = he is at the market
• jde na trh = he goes to the market

Because chodí expresses a habitual / repeated action.

• chodí = he goes / he tends to go / he goes regularly
• jde = he is going / he goes right now in a specific instance

In this sentence, the meaning is general:

• because crowded shops bother him, he goes to the market early in the morning as a habit

So chodí is the right choice.

Compare:

• Dědeček chodí na trh brzy ráno. = Grandfather goes to the market early in the morning (regularly)
• Dědeček jde na trh. = Grandfather is going to the market (now / on one occasion)

Proto means therefore, so, or that’s why.

It links the cause and the result:

• Mému dědečkovi vadí, když je v obchodě moc lidí = crowded shops bother my grandfather
• proto chodí na trh brzy ráno = so / that’s why he goes to the market early in the morning

It is a very useful connecting word in Czech.

Examples:

• Je unavený, proto jde spát. = He is tired, so he goes to sleep.
• Prší, proto zůstáváme doma. = It’s raining, so we are staying home.

Brzy ráno means early in the morning.

• brzy = early
• ráno = morning / in the morning

Together they form a natural time expression:

• brzy ráno = early in the morning

This is just the normal Czech way to say it.

Other similar expressions:

• pozdě večer = late in the evening
• brzo odpoledne = early in the afternoon

Yes. Czech word order is more flexible than English word order, because case endings show the grammatical relationships.

The sentence as given is natural:

• Mému dědečkovi vadí, když je v obchodě moc lidí, proto chodí na trh brzy ráno.

But Czech can move elements around for emphasis or style. For example:

• Když je v obchodě moc lidí, mému dědečkovi to vadí, proto chodí na trh brzy ráno.

That said, not every possible order sounds equally natural. Czech word order often reflects:

• topic vs new information
• emphasis
• style
• rhythm

So while it is flexible, learners should still copy natural patterns rather than moving words randomly.

Because Czech often omits things that English requires, especially dummy subjects like it.

In English, you might say:

• It bothers my grandfather when...

In Czech, you can simply say:

• Mému dědečkovi vadí, když...

The clause když je v obchodě moc lidí functions as what is bothering him, so Czech does not need an extra it.

Sometimes Czech can use to:

• Mému dědečkovi to vadí. = It bothers my grandfather.

But in this sentence, it is not necessary.

No.

• obchod = shop / store
• trh = market

So the sentence contrasts two places:

• he does not like it when there are too many people in the shop
• therefore he goes to the market early in the morning

This may suggest that he prefers shopping at the market, especially before it gets crowded.

It is in the accusative singular.

The preposition na can take different cases depending on meaning:

• na + accusative = motion toward something
• na + locative = location at/on something

So:

• chodí na trh = he goes to the market → motion → accusative
• je na trhu = he is at the market → location → locative

This motion/location contrast is very important in Czech prepositions.