Rukojeť je pod výpletem.

Because pod changes case depending on meaning:

• pod + instrumental = location, where something is
• pod + accusative = direction, where something is moving to

In Rukojeť je pod výpletem, the sentence describes a position, not movement, so Czech uses the instrumental.

• dictionary form: výplet
• instrumental singular: výpletem

A useful contrast:

• Rukojeť je pod výpletem. = it is under it
• Dám rukojeť pod výplet. = I will put the handle under it

Rukojeť is in the nominative singular because it is the subject of the sentence — the thing being described.

You can think of the structure as:

• Rukojeť = subject
• je = verb
• pod výpletem = prepositional phrase telling you where it is

Rukojeť is a feminine noun.

That can be surprising, because it ends in a consonant, and English speakers often first associate consonant endings with masculine nouns in Czech. But some feminine nouns do end in a consonant.

So in a dictionary you would learn it as:

• rukojeť — feminine

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

So:

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

In this sentence, je simply links the subject with its location.

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

So a Czech sentence can often correspond to several English possibilities depending on context:

• the handle is under ...
• a handle is under ...

Czech leaves that kind of definiteness to context instead of using articles.

No, Czech word order is fairly flexible.

Rukojeť je pod výpletem. is a normal, neutral order. But you could also move parts around for emphasis, contrast, or style, for example:

• Pod výpletem je rukojeť.

That still means the same basic thing, but it puts more focus on the location first.

Because Czech uses cases, the grammatical roles are often clear even when the order changes.

Pod usually means under / below.

It does not always use the same case:

• with instrumental → location
  
  • pod stolem = under the table
• with accusative → motion toward a position under something
  
  • pod stůl = under the table (to under the table)

So pod is one of those prepositions where the case tells you whether the sentence is about position or movement.

Výplet is a masculine inanimate noun.

That fits the form you see here:

• base form: výplet
• instrumental singular: výpletem

For masculine inanimate nouns, -em is a very common instrumental singular ending.

A simple learner-friendly guide:

• rukojeť → stress on the first syllable: RU-ko-jeť
• výpletem → stress on the first syllable: VÝ-ple-tem

A few useful pronunciation points:

• Czech stress is almost always on the first syllable
• ť is a soft t-like sound
• ý is a long vowel, so vý- is pronounced longer than a short vy-

So even without perfect phonetics, the most important thing is to keep the stress at the beginning:

• RUkojeť
• VÝpletem

Because the two nouns have different jobs in the sentence.

• rukojeť is the subject, so it stays in the nominative
• výplet comes after pod, and because this is a location phrase, it must be in the instrumental

So the sentence shows a very common Czech pattern:

• subject in nominative
• location phrase after a preposition in the case required by that preposition

Yes, very similar.

For example, nad (above / over) works in the same general way:

• nad + instrumental for location
• nad + accusative for motion

So the pattern is parallel:

• pod výpletem = under it
• nad výpletem = above it

This is a helpful model to remember, because several Czech prepositions behave this way.