Plan rehabilitacji obejmuje ćwiczenie rozciągające i ćwiczenie wzmacniające.

Because rehabilitacji is the genitive singular form of rehabilitacja.

In plan rehabilitacji, Polish is expressing plan of rehabilitation. After many nouns like plan, Polish often uses another noun in the genitive:

• plan rehabilitacji = rehabilitation plan / plan of rehabilitation
• program leczenia = treatment program
• koszt zabiegu = cost of the procedure

A useful question pattern is:

• plan czego? = plan of what?
• rehabilitacji

So rehabilitacji is there because it depends on plan.

Obejmuje normally takes the accusative case, because it means something like includes, covers, or comprises.

So in this sentence, the things included in the plan are in the accusative:

• ćwiczenie rozciągające
• ćwiczenie wzmacniające

However, these forms look exactly like the nominative here. That is normal, because:

• ćwiczenie is a neuter singular noun
• many neuter singular nouns have the same form in nominative and accusative
• the adjectives/participles also match that neuter singular form

So the case is accusative, even though the words do not visibly change.

It is repeated to make it clear that the plan includes two separate exercises/types of exercise:

• ćwiczenie rozciągające
• ćwiczenie wzmacniające

If you said:

• ćwiczenie rozciągające i wzmacniające

that would usually suggest one exercise that is both stretching and strengthening.

So the repetition helps distinguish:

• two different exercises vs.
• one exercise with two qualities

Yes, absolutely. That version is also natural.

It would mean something like The rehabilitation plan includes stretching and strengthening exercises.

Difference in feel:

• ćwiczenie rozciągające i ćwiczenie wzmacniające
  emphasizes two individual exercise types/items
• ćwiczenia rozciągające i wzmacniające
  sounds more general and category-like: stretching and strengthening exercises

In many real-life contexts, the plural version may even sound a bit more natural.

These words agree with ćwiczenie, which is:

• neuter
• singular
• here, in the accusative, though the form looks like nominative

So the describing words also take the neuter singular ending -ące:

• ćwiczenie rozciągające
• ćwiczenie wzmacniające

Compare with other genders:

• ruch rozciągający = a stretching movement
• technika wzmacniająca = a strengthening technique
• ćwiczenie rozciągające = a stretching exercise

The ending changes to match the noun.

They are forms derived from verbs and used like adjectives.

They come from:

• rozciągać = to stretch
• wzmacniać = to strengthen

In this sentence, they function as modifiers of ćwiczenie, so in practice you can think of them as adjective-like words meaning:

• rozciągające = stretching
• wzmacniające = strengthening

More technically, they are related to the active present participle pattern, but for a learner it is often enough to notice that they behave like adjectives and agree with the noun.

Because those are the masculine singular forms.

The noun here is ćwiczenie, which is neuter, so the matching form must also be neuter:

• masculine: rozciągający, wzmacniający
• feminine: rozciągająca, wzmacniająca
• neuter: rozciągające, wzmacniające

Since ćwiczenie is neuter, -ące is the correct ending.

Yes, obejmuje is 3rd person singular present tense.

Its base verb is obejmować:

• ja obejmuję = I include / I cover
• on/ona/ono obejmuje = he/she/it includes
• plan obejmuje = the plan includes

So:

• Plan rehabilitacji obejmuje... = The rehabilitation plan includes...

This is the normal form for stating what a plan contains.

Yes. Polish word order is fairly flexible, though the original version is the most neutral:

• Plan rehabilitacji obejmuje ćwiczenie rozciągające i ćwiczenie wzmacniające.

You could change the order for emphasis, for example:

• Ćwiczenie rozciągające i ćwiczenie wzmacniające obejmuje plan rehabilitacji.

That is grammatical, but it sounds more marked or literary. In normal everyday or textbook Polish, the original order is the safest and most natural.

Usually yes, but the practical meaning can depend on context.

In medical contexts, rehabilitacja often refers to:

• rehabilitation after injury
• physical therapy / physiotherapy-related rehab
• recovery exercises and treatment

So plan rehabilitacji could mean:

• rehabilitation plan
• rehab plan
• in some contexts, a physical therapy plan

The exact English translation depends on the situation, but the Polish word itself is completely normal here.

Roughly: chvee-CHEN-ye

A few helpful notes:

• ćw at the beginning can feel tricky for English speakers
• cz sounds like English ch in chocolate
• nie at the end sounds roughly like nye
• Polish stress is usually on the second-to-last syllable, so:
  ćwi-CZE-nie

So a rough guide is:

• ćwiczenie → chvee-CHEN-ye

Not perfect, but close enough to help you start.

Because it is listing two individual exercise items/types as separate elements of the plan.

Singular version:

• obejmuje ćwiczenie rozciągające i ćwiczenie wzmacniające
  = includes a stretching exercise and a strengthening exercise

Plural version:

• obejmuje ćwiczenia rozciągające i wzmacniające
  = includes stretching and strengthening exercises

Both are correct. The singular version sounds a bit more like a list of specific components, while the plural version sounds broader and more general.