Na rohu ulice zabočíš vlevo a před tebou je starý most.

Because na rohu uses the locative case, which is used after na when it means on/at a location.

• roh = corner
• na rohu = at the corner

If you used na roh, that would suggest motion onto/to the corner, not location.

So:

• na rohu ulice = at the corner of the street

In na rohu ulice, the word ulice is in the genitive singular.

This is because Czech often expresses of relationships with the genitive:

• roh ulice = the corner of the street

So the structure is:

• na rohu = at the corner
• ulice = of the street

Together: at the corner of the street.

Zabočíš comes from the verb zabočit, which means to turn, especially when giving directions.

The ending -íš shows:

• 2nd person singular
• you turn / you will turn

So zabočíš means you turn.

In route instructions, Czech often uses the present form where English also often uses the present:

• zabočíš vlevo = you turn left

Even though it refers to a future action in real life, the present tense is natural in instructions.

Both can relate to left, but they are used slightly differently.

• vlevo = to the left / on the left
• doleva = leftward / toward the left

With verbs of turning, both may appear, but zabočit vlevo is a very common directional phrase.

So:

• zabočíš vlevo = you turn left

For a learner, it is safest to remember vlevo here as the normal adverb used in directions.

Because the preposition před here means in front of, describing a location, so it takes the instrumental case.

The pronoun ty changes like this:

• ty = you
• tebou = by/with/in front of you (instrumental form)

So:

• před tebou = in front of you

If there were motion to a position in front of you, Czech could use a different case, but here it is static location.

Czech usually does not need a separate expression like English there is.

It simply says:

• před tebou je starý most
• literally: in front of you is an old bridge

The verb je means is, and that is enough.

This is very common in Czech:

• Na stole je kniha. = There is a book on the table.
• literally: On the table is a book.

So Czech often expresses existence just with to be plus word order and context.

Both are possible, but they emphasize things differently.

• Před tebou je starý most sounds natural in directions and introduces what you see in that location.
• Starý most je před tebou puts more focus on the old bridge itself.

Czech word order is more flexible than English, and it often depends on what is already known and what is new information.

In directions, it is very natural to start with the place:

• před tebou = in front of you
• then je starý most = there is an old bridge

Because most is a masculine inanimate noun, and the adjective must agree with it.

• most = bridge
• masculine singular nominative

So the adjective starý must also be:

• masculine
• singular
• nominative

That gives:

• starý most = an old bridge

Other forms would match different genders or cases.

Yes. In this sentence, a simply means and.

It links the two parts:

• Na rohu ulice zabočíš vlevo
• a před tebou je starý most

So the whole sentence gives two connected steps in the directions:

1. turn left at the street corner
2. an old bridge is in front of you

It is based on the informal singular you form.

• zabočíš = you (singular, informal)

So this would be appropriate when speaking to one person informally.

For formal or plural you, Czech would use:

• zabočíte

So a more formal/plural version would be:

• Na rohu ulice zabočíte vlevo a před tebou/vámi je starý most.

Usually with formal you, you would also say:

• před vámi = in front of you

Yes, that is close to the Czech structure.

Because zabočíš is formally present tense but often used for instructions about the next action, English can render it as:

• you turn left
• or you’ll turn left

The more natural English translation for directions is usually:

• At the corner of the street, turn left, and in front of you is an old bridge.
• or At the street corner, you turn left and an old bridge is in front of you.

So the Czech present tense in directions does not always match one single English tense exactly.