Le logiciel est censé reconnaître chaque mot-clé, mais aujourd’hui il y a un bug.

Être censé + infinitive means to be supposed to + verb.

So:

• Le logiciel est censé reconnaître... = The software is supposed to recognize...

It is a very common structure in French. After être censé, you normally use an infinitive:

• Je suis censé partir à 8 h. = I’m supposed to leave at 8.
• Nous sommes censés savoir ça. = We’re supposed to know that.

It can describe an expectation, a rule, or what should normally happen.

Because censé agrees with the subject, which here is le logiciel.

• logiciel is masculine singular
• so the form is censé

Compare:

• Le logiciel est censé marcher.
• La machine est censée marcher.
• Les logiciels sont censés marcher.
• Les machines sont censées marcher.

This agreement happens because censé behaves like an adjective after être.

Because after être censé, French uses an infinitive verb.

Pattern:

• être censé + infinitive

So:

• est censé reconnaître
• est censé fonctionner
• est censé corriger les erreurs

This is very similar to English is supposed to recognize, where recognize is also not conjugated.

Because chaque means each, and it is followed by a singular noun in French.

So:

• chaque mot-clé = each keyword

Not:

• chaque mots-clés ❌

Other examples:

• chaque jour = each day
• chaque étudiant = each student

Even though the meaning refers to multiple items one by one, the noun stays singular after chaque.

Both can refer to all the keywords, but the focus is slightly different.

• chaque mot-clé = each keyword, considered individually
• tous les mots-clés = all the keywords, considered as a group

So in a technical context, reconnaître chaque mot-clé suggests the software should identify them one by one.

Because mot-clé is a compound noun meaning keyword.

It is made of:

• mot = word
• clé = key

In the singular, it is:

• un mot-clé

In the plural, it is usually:

• des mots-clés

Here it stays singular because of chaque:

• chaque mot-clé

In il y a, the word il does not mean he in the usual sense.
Il y a is a fixed expression meaning there is or there are.

So:

• il y a un bug = there is a bug

Very common examples:

• Il y a un problème. = There is a problem.
• Il y a deux personnes dehors. = There are two people outside.

You should learn il y a as a set expression.

Both are possible.

• mais aujourd’hui il y a un bug
• mais il y a un bug aujourd’hui

The first version puts a little more emphasis on today, as a contrast:

• normally it should work,
• but today there is a bug.

French often moves time expressions like aujourd’hui to the front for emphasis or flow.

Yes—at least in everyday modern French, especially in tech contexts.

• un bug is very common in spoken and written informal French
• it means a software bug, glitch, or malfunction

There is also the more officially recommended word bogue, but many speakers still say bug. Depending on context, you might also hear:

• un problème
• un dysfonctionnement

But un bug is extremely natural in everyday tech French.

Le logiciel means the software. It refers to a specific piece of software, or to the software already known from context.

If you said Un logiciel, that would mean a piece of software / some software, which is less specific.

So the definite article le is used because the sentence is talking about a particular software system.

Mais means but.

It connects two contrasting ideas:

• Le logiciel est censé reconnaître chaque mot-clé
  the software is supposed to recognize each keyword
• mais aujourd’hui il y a un bug
  but today there is a bug

So mais marks the contrast between what should happen and what is actually happening.

Because aujourd’hui is the standard spelling of the word meaning today.

For a learner, the important thing is simply to memorize it as one fixed word:

• aujourd’hui = today

You do not need to break it apart in normal use. Just remember the spelling, including the apostrophe and the accent marks.

Yes. In standard written French, accent marks matter.

In this sentence:

• censé
• reconnaître
• clé

The accents are part of the correct spelling. They can also help show pronunciation and distinguish words.

For example:

• clé = key
• reconnaître has the circumflex in the standard spelling
• censé needs the accent on the final é

In casual typing, native speakers sometimes omit accents, but in proper French writing you should include them.