Pravítko je na stole vedle knihy, ale já ho vždycky hledám moc dlouho.

Both are possible, but they mean slightly different things.

• Pravítko je na stole... = The ruler is on the table... / A ruler is on the table...
• To pravítko je na stole... adds more specificity, like That ruler or The ruler we’re talking about.

In Czech, bare nouns are often used where English would use the or a, because Czech has no articles.

Because pravítko is a neuter noun in Czech. One clue is its ending -o, which often signals neuter gender.

That matters because it affects:

• agreement with adjectives
• pronouns
• some case endings

Later in the sentence, the pronoun ho refers back to pravítko.

Because the sentence describes location, not motion.

• na stole = on the table → static location
• na stůl = onto the table → movement toward the table

With na, Czech uses:

• locative for location: na stole
• accusative for destination/motion: na stůl

So here:

• Pravítko je na stole = The ruler is on the table but
• Dám pravítko na stůl = I’ll put the ruler onto the table

Because it is in the locative singular after na when expressing location.

The base form is:

• stůl = table

But in the locative singular:

• na stole = on the table

This is just part of Czech declension. Many masculine nouns change form depending on case.

Because the preposition vedle requires the genitive case.

• dictionary form: kniha = book
• genitive singular: knihy

So:

• vedle knihy = next to the book

This is something Czech learners need to memorize: many prepositions always govern a particular case.

It can mean either. In this sentence, vedle knihy is naturally understood as next to the book / beside the book.

Both are good English translations. The Czech phrase itself is very normal and neutral.

That’s true: Czech often omits subject pronouns because the verb ending already shows the person.

So you could say:

• ...ale ho vždycky hledám moc dlouho.

But já is included here for emphasis or contrast:

• ...but I always look for it for too long
• It helps create a contrast with the previous statement: The ruler is on the table..., but I still keep looking for it too long.

So já is not required, but it sounds natural when the speaker wants slight emphasis.

Ho means it here, referring to pravítko.

More specifically:

• it is an unstressed pronoun
• it is used as the direct object
• here it stands for the ruler

So:

• hledám ho = I’m looking for it

In English, it does not change form much, but in Czech pronouns change according to case and sentence role.

Because ho is the accusative form used as the direct object.

Compare:

• to = that/it in some uses, often as a demonstrative or subject/predicate element
• ho = object pronoun, him/it

Here the ruler is what is being searched for, so it is the direct object:

• hledám ho = I’m looking for it

So ho is the right form in this sentence.

Short unstressed pronouns in Czech often appear early in the clause. This is a very common pattern.

So:

• ale já ho vždycky hledám... sounds natural

Czech word order is flexible, but clitic-like short words such as ho tend to come near the beginning of the clause rather than after the main verb.

Vždycky means always.

In this sentence:

• ale já ho vždycky hledám moc dlouho = but I always spend too long looking for it

Czech word order is flexible, so other placements are possible, for example:

• ale já vždycky ho hledám... — less natural
• ale já hledám ho vždycky moc dlouho — possible in special contexts, but not the most neutral

The given order is natural and idiomatic.

Here moc dlouho means too long or for too long.

Literally:

• moc = very / too much
• dlouho = long / for a long time

Together in this context:

• hledám ho moc dlouho = I look for it for too long
• more natural English: it always takes me too long to find it or I always spend too long looking for it

So moc does not always translate neatly word-for-word. It often expresses excess.

Because hledat means to look for / to search for, and the sentence focuses on the process of searching, not the successful result.

• hledám = I am looking for / I look for
• najdu or najít would mean find

So:

• ho hledám moc dlouho = I spend too long looking for it not
• I find it too long

Czech often distinguishes clearly between:

• the ongoing activity: hledat
• the completed result: najít

Yes. Hledám comes from the imperfective verb hledat.

That makes sense because the sentence describes:

• an ongoing activity
• a repeated habit
• the duration of searching

Imperfective verbs are used for that kind of meaning.

A perfective verb would not fit as well here, because the focus is not on the single completed result, but on the repeated experience of searching too long.

Yes. A very literal translation is something like:

• but I always look for it too long

More natural English versions include:

• but it always takes me too long to find it
• but I always spend too long looking for it
• but I can never find it quickly

All of these capture the idea well, even if they do not match each Czech word exactly.

Yes, it sounds natural.

• Pravítko je na stole vedle knihy is a straightforward statement of location.
• ale já ho vždycky hledám moc dlouho is also natural, with the pronoun ho placed early and vždycky in a normal position.

Because Czech word order is flexible, you may see variants, but this version is perfectly idiomatic and good to learn from.