Toto slovo je stopa.

Because slovo is a neuter noun in Czech.

The demonstrative tento / tato / toto changes to match the gender of the noun:

• tento = masculine
• tato = feminine
• toto = neuter

Since slovo is neuter, you say toto slovo.

A few examples:

• tento dům = this house
• tato kniha = this book
• toto slovo = this word

In Czech, many nouns ending in -o are neuter, and slovo is one of them.

So:

• slovo = neuter
• nominative singular = slovo
• the matching form of this is toto

This is something you usually learn together with the noun: not just slovo, but effectively to slovo or at least slovo (neuter).

Stopa is a feminine noun, and many Czech nouns ending in -a are feminine.

So:

• stopa = feminine noun
• basic dictionary form = nominative singular stopa

Even though stopa is feminine, that does not affect toto, because toto agrees with slovo, not with stopa.

Both are in the nominative singular.

In this sentence:

• toto slovo = the subject
• je = is
• stopa = predicate noun

With být (to be), Czech often uses the nominative for this kind of simple identification sentence:

• To je dům.
• Petr je učitel.
• Toto slovo je stopa.

So here stopa is nominative, not accusative.

Because in a basic identifying sentence, Czech normally uses the nominative after být.

So:

• Toto slovo je stopa. = This word is stopa / This word is a trace.

The instrumental, stopou, can appear after být in some contexts, but it usually gives a different feel, often more like:

• a role,
• a function,
• a temporary state,
• or a more stylistic/formal phrasing.

For a straightforward equation or identification, stopa in the nominative is the expected form.

Because Czech does not have articles like English a and the.

So Czech simply says:

• slovo = word / the word / a word
• stopa = trace / a trace / the trace

The exact meaning depends on context.

That means Toto slovo je stopa can be translated naturally into English in different ways depending on context, even though Czech does not mark that difference with articles.

In standard Czech, here you normally do use je.

So:

• Toto slovo je stopa. = correct

Leaving it out would sound incomplete or non-standard in an ordinary sentence.

Czech sometimes omits forms of být in special styles, headlines, notes, or colloquial situations, but for normal learner Czech, you should keep je here.

Sometimes to slovo is possible, but it does not always mean exactly the same thing as toto slovo.

Very roughly:

• toto slovo = this word, more explicitly demonstrative
• to slovo = that/this word, depending on context, often weaker or more context-dependent

For a clear beginner-style sentence meaning this word, toto slovo is a very natural choice.

In everyday spoken Czech, people also often use forms like:

• tohle slovo
• tenhle výraz etc.

But toto slovo is perfectly correct and clear.

The neutral word order here is:

• Toto slovo je stopa.

Czech word order is more flexible than English, but changing the order changes the emphasis.

For example:

• Toto slovo je stopa. = neutral
• Stopa je toto slovo. = marked, unusual, strong emphasis on stopa
• Je to stopa. = It is a trace/clue.
  This is a different structure.

So yes, Czech word order is flexible, but the original sentence is the most straightforward version.

A simple learner-friendly pronunciation guide is:

• toto ≈ TO-to
• slovo ≈ SLO-vo
• je ≈ ye
• stopa ≈ STO-pa

Important pronunciation points:

• Czech stress is usually on the first syllable of each word.
• j is pronounced like English y in yes.
• o is a clear short o, not a diphthong like in many English accents.
• sl at the start of slovo may feel a little awkward for English speakers at first, but it is normal in Czech.

Grammatically, yes — it is correct.

Semantically, it may sound a bit unusual out of context, because slovo means word and stopa means trace / footprint / clue, so the sentence feels like a vocabulary example, a dictionary-style statement, or something said in a language-learning context.

So a Czech speaker would understand it, but in real life it would usually need some context.

It follows a very common pattern:

• demonstrative + noun + být + noun

In this case:

• toto = demonstrative adjective
• slovo = noun
• je = 3rd person singular of být
• stopa = predicate noun

So the structure is basically:

• This word is a trace.

It is a simple equational sentence: one thing is being identified as another.