Il medico rilascia il certificato.

Because Italian uses articles more often than English.

• il medico = the doctor
• il certificato = the certificate / the certificate in question

In this sentence, both nouns are presented as specific, identifiable things, so the definite article il is used with both.

English sometimes drops the where Italian keeps it, so this is something learners notice a lot.

Rilascia comes from the verb rilasciare.

In different contexts, rilasciare can mean things like:

• to release
• to issue
• to hand over
• to provide officially

In the sentence Il medico rilascia il certificato, the most natural meaning is issues or provides a certificate, especially in a formal or medical context.

Rilascia is:

• present tense
• indicative mood
• third person singular

So it matches il medico:

• io rilascio = I issue
• tu rilasci = you issue
• lui/lei rilascia = he/she issues

So Il medico rilascia means The doctor issues.

Because Italian normally does not need subject pronouns when the verb ending already shows the person.

So Italian usually prefers:

• Rilascia il certificato = He/She issues the certificate

If you say Il medico rilascia il certificato, the noun il medico is the subject, so no extra pronoun is needed.

Adding lui would usually sound emphatic, as if you were contrasting him with someone else.

This is the normal Italian word order:

• subject
  • verb
    • object

So:

• Il medico = subject
• rilascia = verb
• il certificato = direct object

This is the most neutral and standard order. Italian can change word order for emphasis, but this version is the basic one learners should know first.

Because il certificato is the direct object of the verb rilasciare.

The doctor is directly issuing the certificate, so no preposition is needed.

Compare:

• Il medico rilascia il certificato = The doctor issues the certificate.

But if you wanted to say to the patient, then you would need a preposition:

• Il medico rilascia il certificato al paziente = The doctor issues the certificate to the patient.

Yes, but the meaning changes.

• il certificato = the certificate
  a specific certificate, or one already understood from context

• un certificato = a certificate
  any certificate, not a specific one

So:

• Il medico rilascia il certificato = The doctor issues the certificate.
• Il medico rilascia un certificato = The doctor issues a certificate.

Because here medico is a noun meaning doctor, and it needs an article in this kind of sentence.

• il medico = the doctor

But after essere, Italian often omits the article with professions:

• Lui è medico = He is a doctor.

So:

• Il medico rilascia il certificato → medico is the subject noun, so it takes an article.
• È medico → profession after essere, usually no article.

In this sentence, il medico is masculine singular: the male doctor or sometimes simply the doctor in a general sense.

For a female doctor, you may hear different forms depending on context and usage, such as:

• la dottoressa
• sometimes la medica
• sometimes la medico in some formal usage

For beginners, the safest contrast is:

• il medico = the male doctor / the doctor
• la dottoressa = the female doctor

A useful approximation is:

• ri-LAH-sha

A couple of pronunciation notes:

• ri sounds like ree
• sci before a sounds like sha

So rilascia is roughly ree-LAH-sha, with the stress on LA.

Yes, if the subject is already clear from context.

Italian often drops the subject when it is understood:

• Rilascia il certificato = He/She issues the certificate.

But if you want to state explicitly who is doing the action, you say:

• Il medico rilascia il certificato.

So the full sentence is more explicit, while the shorter one is more context-dependent.

It is common, but it sounds a bit formal depending on context.

You often see rilasciare in official or institutional situations, for example when someone:

• issues a document
• releases a statement
• grants an authorization

So in a medical or bureaucratic context, Il medico rilascia il certificato sounds very natural. In casual everyday speech, Italians might sometimes choose a different verb depending on exactly what kind of certificate or document they mean.