Pas je v tašce.

Because v is expressing location here, and after v Czech normally uses the locative case.

The dictionary form is taška.
In the locative singular, it becomes tašce.

So:

• taška = bag, handbag, sack
• v tašce = in the bag

This is a very common pattern with feminine nouns ending in -ka:

• škola → ve škole
• taška → v tašce

Notice that k changes to c in this form.

Pas is in the nominative case because it is the subject of the sentence.

The structure is:

• pas = subject
• je = is
• v tašce = in the bag

So Czech is literally structured like:

• Passport is in-bag

The noun naming the thing that is located somewhere stays in the nominative.

Je is the 3rd person singular present tense of the verb být, which means to be.

So:

• jsem = I am
• jsi / jste = you are
• je = he/she/it is
• jsou = they are

In this sentence, pas is singular, so Czech uses je.

If it were plural:

• Pasy jsou v tašce. = The passports are in the bag.

Both v and ve mean in.
Ve is just a pronunciation-friendly variant used before some words or sound combinations.

Here, v tašce is easy enough to say, so v is used.

Compare:

• v tašce
• ve škole
• ve městě
• ve středu

So the choice is mostly about sound and ease of pronunciation, not a difference in meaning.

Yes. Czech word order is more flexible than English word order.

The neutral order here is:

• Pas je v tašce.

But you could also say:

• V tašce je pas.

Both mean the same basic thing, but the emphasis changes.

• Pas je v tašce. → focuses more naturally on the passport
• V tašce je pas. → focuses more on where it is

Czech often changes word order to show emphasis or what information is new.

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

So pas can mean:

• a passport
• the passport

The exact meaning depends on context.

That means Pas je v tašce. could be understood as:

• The passport is in the bag.
• A passport is in the bag.

In real context, one of those will usually be clearly intended.

Yes, pas commonly means passport in Czech.

English speakers sometimes wonder if it might mean belt, but Czech usually uses:

• opasek = belt
• pásek = strap / belt / band, depending on context

So in a normal sentence like Pas je v tašce, pas is understood as passport.

A rough English-style guide is:

pahs yeh f tash-tseh

A few helpful points:

• pas has a short a, like pahs
• je sounds like yeh
• v before a voiceless consonant like t is often pronounced close to f
• š sounds like English sh
• ce here sounds like tseh

So tašce is roughly tash-tseh.

Because Czech distinguishes clearly between:

• location = where something is
• movement toward the inside = into something

So:

• v tašce = in the bag
• do tašky = into the bag

Examples:

• Pas je v tašce. = The passport is in the bag.
• Dám pas do tašky. = I’ll put the passport into the bag.

This is an important difference in Czech.

In normal standard Czech, no. You normally keep je in a sentence like this.

So the correct full sentence is:

• Pas je v tašce.

Leaving out je would sound incomplete in ordinary speech and writing.

You might see omission in very special styles like notes, headlines, or labels, but not as the normal sentence pattern learners should use.