Learn Hardcore Ukrainian: Петро любить жартувати.

Ukrainian doesn’t use a separate word for to with infinitive verbs.
The infinitive itself (жартувати) already means to joke.
So любить жартувати literally is likes joke-to, which in English becomes likes to joke.

What form of the verb is жартувати, and why is it used here?

Жартувати is the infinitive form (the “dictionary form”) of the verb to joke.
After verbs of liking, wanting, starting etc., Ukrainian typically uses an infinitive:

любити + infinitive – to like doing something
So любить жартувати is the regular pattern [likes] + [to joke].

What person and tense is любить, and how would the whole verb любити conjugate?

Любить is 3rd person singular, present tense: he/she/it likes.
Present-tense conjugation of любити (to like, to love) is:

я люблю – I like
ти любиш – you (sg, informal) like
він/вона/воно любить – he/she/it likes
ми любимо – we like
ви любите – you (pl/formal) like
вони люблять – they like

So with Петро you use любить: Петро любить …

Does любить change depending on whether the subject is male or female?

No. In the present tense, любить is the same for he and she.

Петро любить жартувати. – Petro likes to joke.
Марія любить жартувати. – Maria likes to joke.
Gender shows up in adjectives and past tense forms, but not here.

What case is the name Петро in, and is this its base form?

Петро is in the nominative case, which is used for the subject of the sentence.
Yes, this is the base (dictionary) form of the name.
If you address him directly, you’d use the vocative: Петре! (Hey, Petro!)

How do I pronounce Петро любить жартувати?

A rough phonetic guide (stressed syllables in CAPITALS):

Петро – pe-TRO
любить – LIU-bytʲ (the лю is like “lyu”, and final ть is soft, almost like “tʲ”)
жартувати – zhar-tu-VA-ty (Ukrainian ж is like the s in measure)

Stress is on -тро, лю-, and -ва-: Петро ЛЮбить жартуВАти.

Is there any hidden word for is or does here, like in Petro does like to joke?

No. Ukrainian doesn’t use auxiliary verbs like do/does in the present tense, and present-tense to be is usually dropped.
The simple present form любить already covers does like / likes.
So Петро любить жартувати is just a simple present statement about a general habit.

Could I change the word order, for example Жартувати любить Петро?

Yes, Ukrainian word order is flexible.

Петро любить жартувати. – neutral order, just states a fact.
Жартувати любить Петро. – puts more emphasis on жартувати or on Петро as the one who likes joking (e.g. “It’s Petro who likes to joke”).
The grammar meaning doesn’t change; only the focus does.

What is the difference between любити and подобатися when talking about liking something?

Both can translate as to like, but they work differently:

любити + noun/infinitive: more direct, often stronger or more emotional.
- Петро любить жартувати. – Petro likes to joke.
комусь подобається + noun/infinitive: literally “is pleasing to someone”.
- Петрові подобається жартувати. – Joking is pleasing to Petro / Petro likes to joke.

In this sentence, любити жартувати is the most natural, common pattern.

Is жартувати perfective or imperfective, and does that matter here?

Жартувати is imperfective. It describes an action as a process or a repeated/habitual action.
That fits very well after любити, because liking usually refers to a general, habitual activity.
There is a perfective partner пожартувати (to joke once, to have a joke), but
Петро любить пожартувати would sound more like “Petro likes to crack a joke (now and then)”, with a nuance of occasional single acts.

Can жартувати take an object, like “to joke about someone”?

By itself, жартувати just means to joke.
To say “joke about someone / make fun of someone”, you usually add a preposition:

жартувати з когось – to joke about someone, make fun of someone
- Петро любить жартувати з друзів. – Petro likes to joke about his friends.

In Петро любить жартувати, there’s no object, so it’s just the general activity of joking.

Is this pattern любити + infinitive common with other verbs?

Yes, it’s very common. You can use любити + infinitive with many verbs to say you like doing something:

любити читати – to like reading
любити співати – to like singing
любити танцювати – to like dancing

So Петро любить жартувати follows a very typical and useful pattern.