Lekar meri moju temperaturu.

Because lekar is he/the doctor, so the verb has to be in the 3rd person singular.

The present tense of meriti (to measure) goes like this:

• ja merim = I measure / am measuring
• ti meriš = you measure / are measuring
• on/ona meri = he/she measures / is measuring

So:

• Lekar meri... = The doctor is measuring...

Here is the breakdown:

• Lekar = doctor, the subject of the sentence
• meri = measures / is measuring, the verb
• moju = my, agreeing with temperaturu
• temperaturu = temperature, the direct object

So the structure is:

• Lekar → who is doing the action
• meri → the action
• moju temperaturu → what is being measured

Because moj (my) has to agree with the noun it describes in:

• gender
• number
• case

The noun temperatura is:

• feminine
• singular
• here in the accusative case (because it is the direct object)

So moj changes to moju.

A few forms of moj:

• moj = masculine singular
• moja = feminine singular nominative
• moju = feminine singular accusative
• moje = neuter singular

That is why you say moju temperaturu.

Because it is the direct object of the verb meri.

The noun temperatura is a feminine noun that normally ends in -a in the dictionary form (the nominative):

• temperatura = temperature

But in the accusative singular, many feminine nouns ending in -a change to -u:

• temperatura → temperaturu
• knjiga → knjigu
• soba → sobu

So:

• Lekar meri temperaturu. = The doctor is measuring the temperature.

In this sentence, lekar is the subject, so it stays in the nominative case.

• Lekar = nominative singular

Only moju temperaturu changes because it is the object.

So the sentence shows a very common pattern:

• subject in nominative
• object in accusative

Yes. Both lekar and doktor can mean doctor.

A useful distinction:

• lekar = the standard Serbian word for a medical doctor
• doktor = also very common in everyday speech, but can also mean someone with a doctorate

So in a medical context, both are possible:

• Lekar meri moju temperaturu.
• Doktor meri moju temperaturu.

Both are natural.

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

So:

• lekar can mean a doctor or the doctor
• temperaturu can mean a temperature or the temperature, depending on context

Serbian usually lets context show whether something is definite or indefinite.

Yes, very often.

• Lekar meri temperaturu. = The doctor is measuring (my/the) temperature.

In Serbian, possessive words like my, his, her are often omitted when the meaning is obvious from context, especially with things closely connected to a person, such as:

• body parts
• health
• clothing
• personal items

So if it is already clear whose temperature is being measured, moju may sound unnecessary.

Using moju adds emphasis or clarity.

Yes. Serbian word order is more flexible than English because the case endings show the grammatical roles.

The neutral, most straightforward order is:

• Lekar meri moju temperaturu.

But you could also say:

• Moju temperaturu meri lekar.
  This puts more emphasis on my temperature.

Even though the order changes, the endings still show that:

• lekar is the subject
• moju temperaturu is the object

So word order in Serbian often changes for emphasis, focus, or style, not just grammar.

It can mean both, depending on context.

In Serbian, the present tense of an imperfective verb like meriti can express:

• a general action: measures
• an action happening now: is measuring
• a repeated/habitual action: measures regularly

So:

• Lekar meri moju temperaturu.

can mean either:

• The doctor measures my temperature or
• The doctor is measuring my temperature

Context tells you which meaning is intended.

A simple English-friendly approximation is:

LE-kar ME-ri MO-yu tem-pe-ra-TU-ru

A few helpful notes:

• j is pronounced like English y
  • moju sounds roughly like MO-yu
• r is usually trilled or tapped
• stress can vary by dialect and accent, but the approximation above is good enough for a learner

So the whole sentence sounds roughly like:

LE-kar ME-ri MO-yu tem-pe-ra-TU-ru