Tato rychlost je příliš vysoká.

Tato means this and it has to agree with the noun rychlost.

In Czech, this changes form depending on the gender and case of the noun:

• masculine: ten
• feminine: ta / tato
• neuter: to

Because rychlost is a feminine singular noun and here it is in the nominative, the correct form is tato.

You may also hear ta rychlost in less careful or more conversational speech, but tato rychlost is the clear standard form.

Yes, rychlost is feminine.

A lot of Czech feminine nouns do end in -a, but not all of them. Nouns ending in -ost are very often feminine, for example:

• rychlost = speed
• radost = joy
• možnost = possibility

So even though rychlost ends in a consonant, it is still feminine.

The adjective vysoká has to agree with rychlost in:

• gender: feminine
• number: singular
• case: nominative

The basic dictionary form is vysoký. Its nominative singular forms are:

• masculine: vysoký
• feminine: vysoká
• neuter: vysoké

Since rychlost is feminine singular nominative, the correct form is vysoká.

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

So:

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

Because rychlost is singular, Czech uses je:
Tato rychlost je... = This speed is...

Příliš means too, excessively, or overly.

It modifies the adjective vysoká, so:

• vysoká = high
• příliš vysoká = too high

It works much like English too in too high.

Sometimes, yes, but there is a difference in style and clarity.

• příliš vysoká = clearly too high, more neutral/standard
• moc vysoká = often colloquial; depending on context it can feel like too high or sometimes just very high

So if you want to express excess clearly and safely, příliš vysoká is the better choice.

This is a very normal Czech word order:

• Tato rychlost = the topic / subject
• je = is
• příliš vysoká = complement

Czech word order is more flexible than English, but this version is the most straightforward and neutral.

Other orders are possible for emphasis, for example:

• Rychlost je příliš vysoká.
• Příliš vysoká je tato rychlost. — much more marked, used for emphasis or special style

So the original sentence is the natural default choice.

Yes.

If you say:

Rychlost je příliš vysoká.

that means The speed is too high or just Speed is too high, depending on context.

Adding tato makes it more specific: this speed.

Yes. Tahle rychlost is very common in spoken Czech.

Roughly speaking:

• tato rychlost = more neutral, standard, slightly more formal
• tahle rychlost = more conversational, everyday spoken Czech

Both mean this speed.

Czech has no articles like English a or the.

So Czech often expresses definiteness through:

• context
• word order
• demonstratives like ten, ta, to, tato, tahle

That is why rychlost can mean speed, the speed, or even a speed depending on context, while tato rychlost specifically means this speed.

A simple approximate pronunciation is:

TA-to RIKH-lost ye PZHEE-lish VI-so-kaa

A few useful notes:

• Czech stress is normally on the first syllable of each word.
• ch in rychlost is like the ch in Scottish loch or German Bach.
• ř does not appear in this sentence.
• í in příliš is a long vowel.
• á in vysoká is also a long vowel.

A more careful approximation:

• tato = TA-to
• rychlost = RIKH-lost
• je = ye
• příliš = PZHEE-lish
• vysoká = VI-so-kaa

Czech uses vysoký / vysoká / vysoké for things that are high in level, amount, or intensity, including speed.

So:

• vysoká rychlost = high speed
• nízká rychlost = low speed

This matches English quite well here, so příliš vysoká rychlost literally corresponds closely to too high a speed.

It is in the nominative singular.

That is because rychlost is the subject of the sentence:

Tato rychlost je příliš vysoká.
= This speed is too high.

You can see nominative agreement in:

• tato — nominative feminine singular
• rychlost — nominative feminine singular
• vysoká — nominative feminine singular

So the grammar of the whole sentence is nicely aligned around the subject rychlost.