Je vérifie le format de fichier.

Vérifie is the 1st person singular present tense form of vérifier (to check / to verify).

So:

• je vérifie = I check / I am checking

In French, the present tense often covers both English meanings:

• I check
• I am checking

The exact meaning depends on context.

French only shortens je to j' before a vowel sound or a mute h.

So you get:

• j'aime because aime starts with a vowel
• j'habite because habite starts with a mute h

But here the next word is vérifie, which starts with the consonant sound v, so it stays:

• je vérifie

Le is the definite article, meaning the.

So:

• le format = the format

French uses articles very regularly, often more regularly than English. In this sentence, le format refers to a specific format being checked, or to the file format as the relevant thing under discussion.

If you wanted a format, you would say:

• un format

So:

• Je vérifie le format de fichier. = I’m checking the file format.
• Je vérifie un format de fichier. = I’m checking a file format.

This is one of the most useful things to notice in the sentence.

Format de fichier is a common French structure meaning file format. It works like a noun + de + noun combination.

So:

• format de fichier = file format

Here, de fichier is being used in a general/classifying sense: it describes what kind of format it is.

By contrast:

• le format du fichier

means the format of the file, usually a specific file

So the difference is roughly:

• format de fichier = file format (as a type/category/technical term)
• format du fichier = the format of the file (a particular file)

In many real situations, if you mean one specific file on your computer, Je vérifie le format du fichier may sound more natural.

Because after de, French often leaves out the article when the second noun is being used to classify the first noun.

That is exactly what happens in:

• format de fichier

This is similar to other French combinations like:

• salle de classe = classroom
• serviette de bain = bath towel
• manuel d'utilisation = user manual

The second noun is not always being treated as a separate, fully specified noun with the/a. Instead, it helps define the type of thing.

The sentence follows a very normal French order:

• Je = subject
• vérifie = verb
• le format de fichier = direct object

So the pattern is:

• Subject + Verb + Object

Inside the object, French uses:

• format de fichier

where English often uses a noun before another noun:

• file format

English likes noun + noun French often prefers noun + de + noun

That is why French says format de fichier rather than something like fichier format.

A rough pronunciation guide is:

zhuh vay-ree-fee luh for-mah duh fee-shyay

A few helpful notes:

• je sounds like zhuh
• vérifie has the stress pattern typical of French; do not heavily stress one syllable like in English
• format ends with a clear a sound, not like English format
• fichier is pronounced roughly fee-shyay

A more French-like breakdown would be:

• Je → zhuh
• vérifie → vay-ree-fee
• le → luh
• format → for-ma
• de → duh
• fichier → fee-shyay

In connected speech, some of these vowels may become very light.

Yes, it is understandable and grammatically fine, especially in a technical or computing context.

However, depending on what you mean, a native speaker might also say:

• Je vérifie le format du fichier.

That version is often more natural if you mean one specific file.

So:

• Je vérifie le format de fichier. = I’m checking the file format / the file-format type
• Je vérifie le format du fichier. = I’m checking the format of the file

Both are possible, but they are not exactly the same in nuance.

Yes. French very often uses the simple present where English uses either:

• I check
• I am checking

So:

• Je vérifie can mean I check or I’m checking

If you want to emphasize that the action is happening right now, French can also use:

• Je suis en train de vérifier le format du fichier.

This means:

• I am in the middle of checking the file format
• more literally, I am in the process of checking the file format

But in everyday French, Je vérifie... is usually enough.