Глоссарий включает терминологию проекта.

Терминологию is in the accusative case because it is the direct object of the verb включает (includes).

• включает что? — терминологию
• Nominative: терминология
• Accusative: терминологию

This is a very common pattern in Russian: a transitive verb takes its direct object in the accusative.

Проекта is in the genitive case because it means of the project.

So:

• терминология проекта = the terminology of the project / the project's terminology

This is one of the most common uses of the genitive in Russian: showing possession, relationship, or specification.

Compare:

• книга студента = the student's book
• центр города = the city center
• терминология проекта = the terminology of the project

Включает is a conjugated verb, while включать is the infinitive.

Here, the sentence needs a finite verb meaning includes, so Russian uses:

• включает = includes

It is the 3rd person singular present tense form of включать.

Because the subject is глоссарий (glossary), the verb must match it:

• глоссарий включает = the glossary includes

Yes, глоссарий is masculine singular.

Many Russian masculine nouns end in a consonant, but some also end in -й or -ий, and they are still masculine. Глоссарий is one of those.

That is why the verb is singular:

• глоссарий включает

If it were plural, you would have:

• глоссарии включают = glossaries include

The given word order is the most neutral and natural one:

• Глоссарий включает терминологию проекта.

Russian word order is more flexible than English word order because cases show grammatical roles. So other orders are possible, for example for emphasis:

• Терминологию проекта включает глоссарий.

But that sounds more marked or stylistic. For a learner, the original order is the safest default:

subject + verb + object

Russian does not have articles like the or a/an.

So:

• глоссарий can mean the glossary or a glossary
• проекта can mean of the project or of a project

Which one is meant depends on context. In many practical translations, English adds the because it sounds natural:

• The glossary includes the project's terminology
• The glossary includes terminology for the project

Russian simply does not mark this with articles.

Not exactly. Терминология usually means terminology as a system or body of specialized terms, not individual terms one by one.

So this sentence sounds a bit more formal than saying:

• Глоссарий включает термины проекта.
  = The glossary includes the project's terms.

Both can work, but:

• терминология = the terminology as a whole
• термины = individual terms

Yes, depending on context, English may translate it a few different ways.

Literally, терминология проекта is the terminology of the project. But in smoother English, that may become:

• the project's terminology
• terminology used in the project
• project terminology

The Russian genitive here mainly shows a close relationship between terminology and project. The exact English wording depends on style and context.

Включает comes from the imperfective verb включать.

In Russian, the present tense normally uses the imperfective aspect. Here it expresses a general fact:

• The glossary includes...

That is why включает is natural.

The perfective partner is включить, but perfective verbs do not normally have a true present-tense meaning. Their present-looking forms usually refer to the future.

So:

• включает = includes / is including
• включит = will include

The stress is:

• Глосса́рий включа́ет терминоло́гию прое́кта.

A rough pronunciation guide:

• Глосса́рий = gla-SA-reey
• включа́ет = fklyu-CHA-yet
• терминоло́гию = tir-mi-na-LO-gi-yu
• прое́кта = pra-YEK-ta

Stress is important in Russian, because it is not always predictable from spelling.

Yes, absolutely. Содержит (contains) is also natural here.

Compare:

• включает = includes
• содержит = contains

Both are possible, but there is a slight nuance:

• включает suggests this is one component among others
• содержит focuses more on what is inside

So both of these are good Russian:

• Глоссарий включает терминологию проекта.
• Глоссарий содержит терминологию проекта.

It is grammatically correct and natural, but it does sound a bit formal or technical, which makes sense for words like глоссарий and терминология.

This is the kind of sentence you might see in:

• software documentation
• project documentation
• educational materials
• technical writing

In casual everyday speech, people might use simpler wording, but in a professional context this sentence is perfectly normal.