V této zemi žijí psi a kočky.

Dogs and cats live in this country.

Breakdown of V této zemi žijí psi a kočky.

• pes: the dog
• kočka: the cat
• a: and
• v: in

Questions & Answers about V této zemi žijí psi a kočky.

Why is it v této zemi?

Because v means in, and when it expresses location in Czech, it normally requires the locative case.

So:

• země = country / land
• v zemi = in the country
• v této zemi = in this country

Both této and zemi are in the locative singular here.

Why does tato become této?

Tato is the basic feminine singular form of this.

But Czech words change their endings depending on case. Since v here requires the locative, tato changes to této.

So the pattern is:

• tato země = this country
• v této zemi = in this country

This is normal adjective/demonstrative agreement: the demonstrative must match the noun in gender, number, and case.

Why does země become zemi?

Because země is in the locative singular after v.

Its dictionary form is:

• země = nominative singular

But in this sentence you need:

• v zemi = locative singular

So:

• země → zemi

This is a common kind of change for feminine nouns.